Fact-checked by Grok 2 weeks ago

Tertian

''Tertian'' is derived from the Latin ''tertianus'', meaning "of the third". The term has applications in several fields. In , it describes a type of recurring every 48 hours (every third day inclusively), most commonly associated with caused by '''' or ''''. In music theory, tertian refers to , chords, or structures built by stacking intervals of major and minor thirds. In religion, particularly within the Society of Jesus (), a tertian is a member undergoing tertianship, the final stage of formation involving spiritual renewal and preparation for final vows.

Etymology

Origins

The term "tertian" derives from the Latin adjective tertiānus, meaning "of the third," which originally described phenomena occurring every according to ancient inclusive reckoning, where days were counted starting from the current one. This etymology stems from the Latin root tertius, signifying "third," and reflects a broader application to periodic events that recur at intervals of two intervening days. The word entered English around 1362, as evidenced by its appearance in William Langland's Piers Plowman, where it was borrowed directly from Latin, likely influenced by intermediaries such as terciane. This early adoption highlighted its utility in denoting rhythmic or cyclical patterns, laying the groundwork for its linguistic persistence in describing third-based structures. By the , it had begun appearing in medical texts to characterize recurring fevers.

Evolution of usage

The term "tertian," derived from the Latin tertius meaning "third," entered English usage in the primarily within medical contexts to denote a fever recurring every , drawing from traditions as translated and elaborated in medieval and . This medical connotation dominated scholarly and clinical writings through the 17th century, where it appeared frequently in discussions of intermittent fevers influenced by the works of and , whose texts on periodic illnesses like tertian types were widely disseminated in European universities and pharmacopeias. By the 16th century, the term found adoption in religious formation within the Society of Jesus, where "tertian" referred to the third and final probationary period for before final vows, emphasizing spiritual discernment and renewal as outlined by St. . This usage, independent of medical origins, highlighted a structural "third" phase in vocational training, becoming a standard element of from the order's founding in onward. In 19th-century , such as Webster's 1828 , "tertian" retained its primary definition as an or ague returning every other day (counting inclusively), with secondary references to a unit of liquid measure, underscoring its entrenched medical association amid evolving understandings of and periodic diseases. The application of "tertian" expanded into in the 20th century, where it described structures and chords constructed by stacking intervals of thirds, distinguishing traditional Western tonal practices from emerging quartal and systems in modernist composition. This semantic shift reflected broader analytical trends in examining interval-based organization, with the term gaining prominence in pedagogical texts amid the rise of extended harmonies in and .

Medicine

Tertian fever

Tertian fever refers to a of characterized by paroxysms that recur every 48 hours, which ancient physicians counted as every third day by including the day of onset. This periodicity distinguishes it from quotidian fever, which occurs daily, and , which recurs every 72 hours. The term originates from the Latin febris tertiana, denoting a fever returning on the third day in inclusive reckoning, such as a paroxysm on followed by the next on Thursday. The pattern was first systematically recognized in by around the 5th century BCE, who classified it as one of four principal types of periodic fevers, often linked to marshy environments and humoral imbalances. Hippocratic texts, such as the Epidemics, describe tertian fevers with their characteristic cycles of chills, rigor, high temperature, and profuse sweating, interpreting the "crisis" on the third day as a potential turning point in the illness if untreated. In modern pathology, tertian fever is primarily associated with malaria infections caused by the protozoan parasites or . These species exhibit an erythrocytic cycle of approximately 48 hours, during which schizonts mature and rupture red blood cells, releasing merozoites that synchronize subsequent invasions and trigger the febrile paroxysms of chills, fever peaking at 40–41°C, and diaphoresis. Historically, this association evolved from observations of periodic fevers in endemic regions, solidifying tertian as a hallmark of benign vivax malaria in contrast to more severe forms.

Clinical characteristics and diagnosis

Tertian fever, primarily associated with Plasmodium vivax or Plasmodium ovale malaria, manifests as a cyclical illness characterized by paroxysmal attacks recurring every 48 hours, historically noted as occurring every third day. Each episode typically unfolds in three distinct stages: an initial cold stage lasting 15 to 60 minutes, marked by intense chills and shivering due to ; a subsequent hot stage enduring 2 to 6 hours, featuring high fever often reaching 40–41°C (104–106°F), accompanied by severe , , vomiting, myalgias, and arthralgias; and a final sweating stage involving profuse , gradual defervescence, and profound fatigue as the temperature normalizes. Between attacks, patients may experience relative well-being, though persistent symptoms like mild or can occur. The pathophysiology of tertian fever stems from the intraerythrocytic lifecycle of the parasite, where merozoites invade reticulocytes (young red blood cells) and mature into trophozoites, schizonts, and eventually rupture the host cells after approximately 48 hours, synchronously in a significant portion of infected erythrocytes. This rupture releases daughter merozoites to infect new cells, along with parasite-derived toxins and cellular debris, triggering an intense response (including TNF-α and IL-1) that drives the febrile paroxysm. Unlike P. falciparum, P. vivax preferentially targets reticulocytes, limiting peak parasitemia to 2–3% and reducing the risk of severe microvascular obstruction, though hypnozoites dormant in the liver can cause relapses months to years later. Diagnosis of tertian fever relies on a combination of clinical history and confirmation, with a travel history to endemic areas being crucial for suspicion. The gold standard is microscopic examination of Giemsa-stained thick and thin blood smears, where thick smears detect parasites with high sensitivity and thin smears identify P. vivax by its characteristic large, ameboid trophozoites and in infected erythrocytes; smears are ideally collected during or just after a fever paroxysm. Rapid diagnostic tests (RDTs) targeting P. vivax-specific (pLDH) offer quick results with 95% sensitivity and 99% specificity in field settings, while (PCR) provides definitive species identification, particularly useful for low-parasitemia cases or distinguishing from other species. If untreated, tertian malaria can lead to complications such as from repeated erythrocyte destruction, due to reticuloendothelial hyperplasia, and rarely severe manifestations like (ARDS), renal failure, or splenic rupture (mortality rates of 10–38%, higher among travelers). is uncommon but possible in severe cases, and pregnant individuals face heightened risks of , prematurity, or . Most uncomplicated cases respond well to antimalarials like (total dose 1,500 mg base over 3 days), though emerging resistance in some regions necessitates alternatives such as artemisinin-based combination therapies; is added to eradicate hypnozoites and prevent relapses. Differentiation from other malarial fevers includes its 48-hour cycle, shorter than the 72-hour of P. malariae and longer than the daily (quotidian) spikes sometimes seen in P. falciparum or P. knowlesi infections.

Music theory

Definition and principles

Tertian refers to musical structures, including chords, progressions, and scales, that are constructed by stacking intervals of major or minor . A major third encompasses four semitones, such as the interval from C to E, while a minor third spans three semitones, such as from A to C. These intervals form the foundational building blocks, with chords arising from successive superimpositions starting from a root note. The core principles of tertian harmony center on the superposition of thirds to create root-position chords, where the root serves as the lowest note and subsequent thirds are added above it to build harmonic entities like s and seventh chords. In this system, a basic results from stacking two thirds—a or third followed by another—yielding structures such as , , diminished, or augmented s based on the interval qualities. Extended chords incorporate thirds, where additional or thirds are layered beyond the , forming , eleventh, or thirteenth chords while maintaining the tertian framework. This tertian approach stands in contrast to other harmonic systems, such as quartal harmony (built on stacked fourths) or quintal harmony (built on stacked fifths), which prioritize different intervals for chord construction. Tertian harmony's theoretical foundation lies in its emphasis on the inherent consonance of stacked thirds, which has made it a dominant feature of Western tonal music since the , underpinning the vertical sonorities in polyphonic and homophonic textures.

Applications in harmony and composition

In tertian harmony, triads form the foundational chord types, constructed by stacking two thirds: a major triad consists of a major third over a minor third (e.g., C-E-G), while a minor triad features a minor third over a major third (e.g., A-C-E). Seventh chords extend this structure by adding a third above the triad, resulting in four superimposed thirds, such as the major seventh (C-E-G-B) or minor seventh (A-C-E-G). Further extensions include ninth chords (adding a ninth, or second above the octave), eleventh chords, and thirteenth chords, which continue the tertian stacking to create richer sonorities prevalent in jazz and modern composition. Permutations of these stacked thirds yield distinct chord qualities: the arises from two major thirds (e.g., C-E-G♯), producing symmetrical tension suitable for modulatory pivots; the uses two minor thirds (e.g., B-D-F), offering dissonant leading tones for resolution; and the combines a major third followed by two minor thirds (e.g., G-B-D-F), driving harmonic motion through its between the third and seventh. Historically, tertian principles underpin and Classical harmony, as seen in Johann Sebastian Bach's chorales, where progressions of triads and seventh chords provide functional stability and voice-leading smoothness within diatonic frameworks. In the 20th century, jazz composers like adapted these concepts through rapid modulations cycling by major thirds—known as —replacing standard ii-V-I progressions with sequences of dominant seventh chords to heighten chromatic intensity and potential. Diatonic scales facilitate tertian construction, as their stepwise intervals alternate to form third successions in chords (e.g., the scale yields triads like C-E-G and D-F-A). In , voice leading in tertian progressions emphasizes common tones between chords—such as the shared third or fifth—to ensure smooth transitions and minimize leaps, a central to coherent development. Tertian inversions rearrange these stacked thirds, often producing sixth chords that enhance bass flexibility; for instance, the first inversion of a minor triad (e.g., C-A in an A minor context) creates a sixth interval from bass to root, functioning as a passing or preparatory harmony in progressions.

Religion

Tertianship in the Jesuits

Tertianship serves as the final stage of formation in the Society of Jesus, providing Jesuit scholastics with a period of intensive spiritual renewal typically lasting eight to nine months in preparation for final vows. This phase allows participants, who have already completed earlier stages of training, to deepen their commitment through reflection on their vocation and integration of prior experiences into Ignatian principles. The term "tertian" derives from the Latin tertius, signifying "third," as it represents a third probationary period akin to an extension of the novitiate. Historically, tertianship was instituted by Ignatius of Loyola in the 16th century as part of the Society's foundational structure, formalized in the Constitutions by 1558 following years of practical experimentation within the order. Loyola envisioned this stage to renew the spirit of piety among members and equip them to apply their learning and ministry experience more effectively in service to the Church. Drawing from his own transformative encounters, Ignatius rooted the practice in the Spiritual Exercises, emphasizing total conformity to God's will and devotion to Christ as core inspirations for this culminating formation. Entry into tertianship is not automatic but requires an invitation from the , extended after completing studies, a period of regency, formation (often including for priests), and several years of active ministry. This discernment process ensures that only those deemed ready for deeper incorporation proceed. The key elements of tertianship center on , including a full repetition of the —often through a 30-day —and communal to foster ongoing conversion and apostolic readiness. Participants engage in , study of Jesuit documents, and limited ministry to integrate intellectual, spiritual, and practical dimensions of their calling.

Structure and purpose

Tertianship in the Society of Jesus involves a structured period of immersion in contemplative prayer, a 30-day based on the of St. Ignatius, hands-on apostolic work such as service among the marginalized, and periods of theological reflection on the Jesuit Constitutions and charism. This formation often occurs in international settings, historically including sites like Abbey in , to foster a global perspective on Jesuit . The program's duration is flexible, typically ranging from three to twelve months or sometimes split across sessions, allowing adaptation to individual circumstances and provincial needs. The primary purpose of tertianship is to deepen the Jesuit's union with , integrate prior formation experiences into a cohesive vocational commitment, and prepare candidates for final incorporation as priests or brothers in the . It emphasizes cultivating humility, obedience, and affective love for the divine, often described as "the school of the heart" in the Ignatian tradition. Through these elements, tertianship equips participants to align their lives more fully with the apostolic goals of the , promoting interior freedom and readiness for lifelong service. Following the Second Vatican Council, modern tertianship has incorporated adaptations reflecting the Church's call for renewal in religious life. These changes allow for tailored experiments in structure, approved by the Superior General, to address contemporary regional contexts while maintaining core Ignatian principles. Tertianship culminates in the final profession of perpetual vows of poverty, chastity, and obedience, marking full membership in the Society of Jesus. Historical examples include Pedro Arrupe, who completed his tertianship in Cleveland, Ohio, in 1937–1938, incorporating pastoral work with immigrants that foreshadowed his later global leadership as Superior General. This stage thus serves as a transformative probation, ensuring Jesuits emerge with renewed commitment to their vocation.

References

  1. [1]
    TERTIAN Definition & Meaning - Merriam-Webster
    The meaning of TERTIAN is recurring at approximately 48-hour intervals —used of malaria.
  2. [2]
    TERTIAN Definition & Meaning | Dictionary.com
    Tertian definition: (of a malarial fever, etc.) characterized by paroxysms that recur every other day.. See examples of TERTIAN used in a sentence.
  3. [3]
    Malaria - Medical Microbiology - NCBI Bookshelf - NIH
    The most characteristic symptom of malaria is fever. Other common symptoms include chills, headache, myalgias, nausea, and vomiting. Diarrhea, abdominal ...
  4. [4]
    Malaria: Practice Essentials, Background, Etiology
    The classic description is a quartan (every 72 hours) or tertian (every 48 hours) fever periodicity synchronized with Plasmodium merozoites bursting from red ...
  5. [5]
    tertian | Taber's Medical Dictionary
    (tĕr′shŭn ) [L. tertianus, the third] Occurring every third day; usually pert. to a form of malarial fever. Citation. Venes, Donald, editor. "Tertian.Missing: definition | Show results with:definition
  6. [6]
    Malaria
    Three basic types of malaria. 1. Benign tertian (P vivax and P ovale) with a fever every 2nd day (e.g., Monday; fever, Tuesday; no fever, Wednesday; fever).
  7. [7]
    Final Diagnosis -- Malaria (Intermittent fevers)
    Infection with P. malaria causes paroxysms every 72 hours (quartan malaria). Infection with P. ovale or P. vivax cause tertian malaria with paroxysms every 48 ...
  8. [8]
    Tertian and quartan fevers: temporal regulation in malarial infection
    The cyclic fever that characterizes malarial infections is the outward manifestation of the parasite development. Until recently, little was known about the ...
  9. [9]
    Tertian and Quartan Fevers: Temporal Regulation in Malarial Infection
    Fevers and chills generally occur every third day in. Plasmodium falciparum, 2 days for Plasmodium vivax infections, and every 4 days in the case of Plasmodium.<|control11|><|separator|>
  10. [10]
    Classification of malaria by the clinical pattern of fever
    Feb 13, 2023 · This has led to the description of malaria as being either tertian, where fever occurs every third day i.e. day 1,3,5 etc. or quartan where ...
  11. [11]
    Malaria | About Neglected Tropical Diseases and Three ... - Eisai
    It is when these red blood cells rupture that malarial symptoms or attacks occur. Usually, malarial attacks will happen every other day with “tertian parasites” ...
  12. [12]
    Tertian - Etymology, Origin & Meaning
    Originating in late 14c. from Latin tertianus (from tertius, "third"), late originally meant "occurring every other day," especially for fevers.
  13. [13]
    tertian, adj. & n. meanings, etymology and more
    There are ten meanings listed in OED's entry for the word tertian, two of which are labelled obsolete. See 'Meaning & use' for definitions, usage, and quotation ...Missing: definition | Show results with:definition<|control11|><|separator|>
  14. [14]
    Medicine from Galen to the Present: A Short History - PMC - NIH
    Medieval medicine was heavily influenced by the ancient Greeks and Romans, in particular by Hippocrates and Galen.
  15. [15]
  16. [16]
    Jesuit Terms T - Xavier University
    The name comes from the Latin word for "third," and so this stage is sometimes called "third probation" (the first two years of probation being the novitiate ...
  17. [17]
    TERTIANSHIP Definition & Meaning - Merriam-Webster
    a third period of novitiate or training undertaken by a Jesuit after ordination. Word History. Etymology. tertian entry 2 + -ship. The Ultimate Dictionary ...
  18. [18]
    Webster's Dictionary 1828 - Tertian
    TER'TIAN, noun A disease or fever whose paroxysms return every other day; an intermittent occurring after intervals of about forty eight hours. 1. A measure of ...Missing: definition | Show results with:definition
  19. [19]
    Webster's Dictionary 1828 - Ague
    It is used for a periodical fever, an intermittent, whether quotidian, tertian, or quartan. In this case, the word, which signifies the preceding cold fit ...Missing: 19th century
  20. [20]
    Rameau and eighteenth-century harmonic theory (Chapter 24)
    This chapter traces many of these concepts and their attendant pedagogical traditions as inherited by the early eighteenth century.
  21. [21]
    History of extended tertian chords in jazz - SMT Discuss
    Dec 29, 2016 · I am trying to figure out when and if possible how extended tertian sonorities (especially "eleventh" and "thirteenth" chords) became standard ...<|separator|>
  22. [22]
    Periodic pyrexia and malaria in antiquity : history of medicine : SAMJ ...
    We must remember that the Greeks counted their days from the day of onset of the illness – a fever 48 hours later would thus fall on their third day (thus ...Missing: etymology | Show results with:etymology
  23. [23]
    Akhawayni and the first fever curve - PubMed
    By the time of Hippocrates the typical paroxysmal fever patterns of tertian (every 48 hours) and quartan (every 72 hours) fevers caused by malaria were known.
  24. [24]
    TERTIAN definition in American English - Collins Dictionary
    1. occurring every other day so that it happens on the first and third days: usually applied to fever or a disease causing it, esp.
  25. [25]
    Malaria in Europe: A Historical Perspective - PMC
    Hippocrates (460-370 BC) described episodes of benign tertian fever that have been interpreted as P. vivax malaria, while the term quartan fever could refer to ...
  26. [26]
    A History of Malaria and Conflict | Parasitology Research
    Mar 20, 2024 · While those with crises on odd days, the first interval is on the third day ... ” Tertian fever most likely refers to P. vivax infection ...
  27. [27]
    Journey of Scientific Discoveries - Malaria Site
    Thus, fever recurring on Tuesday and Thursday was called a tertian or “every third day” fever, although only forty-eight hours separated the two attacks. A ...
  28. [28]
    Plasmodium vivax Malaria - StatPearls - NCBI Bookshelf - NIH
    Jul 17, 2023 · While parasitemia rarely exceeds 2-3%, P. vivax can still result in significant disease due to increased host immune response[6]. Parasites ...
  29. [29]
    Review The pathophysiology of vivax malaria - ScienceDirect.com
    Long considered a benign infection, Plasmodium vivax is now recognized as a cause of severe and fatal malaria, despite its low parasite biomass.Missing: symptoms | Show results with:symptoms
  30. [30]
    Clinical impact of vivax malaria: A collection review | PLOS Medicine
    Jan 18, 2022 · Malaria caused by P. vivax was termed benign tertian malaria because the clinical course was generally considered to be mild compared to ...
  31. [31]
    32.3 Quartal, Quintal, and Secundal Harmony
    Secundal harmony refers to chords stacked entirely (or mostly) in seconds. Contrast these concepts with the tertian (stacked in thirds) harmony we've ...
  32. [32]
    13. Triads – Fundamentals, Function, and Form - Milne Publishing
    In a major triad, the interval from the root to the third is a major third; in a minor triad it is a minor third. ... Note: A tertian harmony is one that is ...
  33. [33]
    [PDF] Lesson I: Notation of Pitch - Christopher Newport University
    Tonal music relies on the tertian principle, which builds harmonies by configuring notes into clusters of major and minor thirds. The most basic tertian entity ...
  34. [34]
    Lesson 3b - Seventh Chords - Integrated Music Theory
    Because they are stacked thirds, seventh chords are still considered tertian harmony. They are prevalent in almost all styles of Western music, and we have ...
  35. [35]
    Chord Extensions - The Complete Guide - Piano With Jonny
    Mar 31, 2023 · The first step to playing extended chords is to learn the 3 chord extensions that can be applied to seventh chords. They are the 9th, 11th and ...
  36. [36]
    What is an augmented chord - Skoove
    Sep 28, 2021 · An augmented chord has a raised fifth note by a half step, is composed of two stacked major thirds, and has the formula 1-3-#5.<|control11|><|separator|>
  37. [37]
    Augmented & Diminished Chords | Piano Lessons Near Waltham
    Sep 16, 2024 · Diminished chords are built with two minor thirds, while augmented chords are built with two major thirds. Augmented chords do not occur ...
  38. [38]
    Harmonic Dissonance II: The Seventh Chord – Composing Music
    The seventh chord is a four note tertian chord, containing a fourth chord tone, the seventh. This tone is added to a triad a distance of a third above the ...Major Mode: Seventh Chord... · Major Mode Diatonic Triads... · Connecting Seventh Chords To...
  39. [39]
    [PDF] the harmonic implications of the non-harmonic tones - CORE
    May 4, 2013 · Tertian harmony is harmony based on the interval of a third. ... However, the sample of Bach's music was not solely the four-part chorales ...
  40. [40]
    Coltrane Changes Explained - TJPS - The Jazz Piano Site
    Coltrane Changes are a chord progression that changes keys by Major 3rd intervals. Coltrane didn't invent this idea but was the first to use it extensively.
  41. [41]
    Giant Steps, Central Park West, and Modulatory Cycles
    Coltrane creates the initial pattern, interrupts it with a tangential move to D, and then restores and completes it via tritone modulation from D to Ab. Rather ...
  42. [42]
    Diatonic Scale 101: Theory Essentials For Inspired Producers
    Jun 27, 2024 · Diatonic chords are built from the notes of diatonic scales, and each scale degree can be used to form a triad (which is a three-note chord).
  43. [43]
    Voice-Leading I: Common-Tone Chords in the Major Mode
    In this chapter we will learn how to connect chords together into harmonic progressions, forming short phrases in a chosen diatonic major key.7 Voice-Leading I... · Chord Connection And Phrase... · Voice Leading
  44. [44]
    6th Chords - The Complete Guide - Piano With Jonny
    May 4, 2023 · Another way to build a major 6th chord is to start with a major triad and add a major 6th interval above the root. (Think: Root, 3rd, 5th, 6th).Missing: tertian | Show results with:tertian
  45. [45]
    Tertianship - Jesuit Vocations
    Tertianship is a time of renewal. A Jesuit revisits the foundational documents and history of the Society of Jesus.Missing: definition origins
  46. [46]
    CATHOLIC ENCYCLOPEDIA: The Jesuits (The Society of Jesus)
    The Society of Jesus is a religious order founded by Saint Ignatius Loyola. Designated by him "The Company of Jesus" to indicate its true leader and its ...
  47. [47]
    Tertianship - Jesuits.org
    Tertianship. After three to five years in active ministry, a Jesuit spends a period of time in a tertianship program ranging from nine weeks over two summers ...Missing: medieval novitiate
  48. [48]
    Become a Jesuit
    Final Vows: After completing tertianship and subject to the approval of his provincial and the Jesuit superior general, the Jesuit is invited to take final vows ...
  49. [49]
    "Tertianship is the school of the heart" | Jesuit Conference of Asia ...
    Mar 20, 2019 · Tertianship is the final period of formal religious formation for Jesuit priests and brothers, during which the Jesuit makes the full Spiritual Exercises again.
  50. [50]
  51. [51]
    Milltown Park - Irish Jesuit Archives
    1903-1904 He made Tertianship at Drongen, Belgium 1904-1906 He was Director and Editor of the Irish Messenger, taught and was Prefect ...
  52. [52]
    Tertianship - USA East Province - Jesuits East
    A Jesuit spends a period of time in a tertianship program ranging from nine weeks over two summers to nine months to prepare for his Final Vows.
  53. [53]
    Decree 10: “Tertianship,” General Congregation 31 (1966)
    Tertianship is essentially a year of probation, when a Jesuit examines his vocation before taking final vows. In the following decree, the delegates encourage ...Missing: etymology tertian
  54. [54]
    Pedro Arrupe, Hiroshima and the Sacred Heart - America Magazine
    Jun 27, 2025 · At the time, he was in Cleveland, Ohio, completing the final stage of Jesuit formation—the year of spiritual renewal known as tertianship.