adjuvant

English

WOTD – 19 August 2025

Etymology

Learned borrowing from Latin adiuvant-, adjuvant- + English -ant (suffix forming adjectives with the sense ‘exhibiting a condition or process’; and forming agent nouns). Adiuvant-, adjuvant- are oblique stems of adiuvāns, adjuvāns (assisting, helping), the present active participle of adiuvō (to assist, help; to be useful; etc.), from ad- (prefix meaning ‘to; toward’) + iuvō (to aid, help; to save) (possibly from Proto-Indo-European *h₁ewH- (to assist, help; to save)).[1]

Adjective sense 3 (“of a form of therapy or treatment: additional, supplementary”) and noun sense 1.4 (“additive which aids or modifies the action of the principal ingredient of a drug”) are possibly derived from French adjuvant (adjective, noun).[1]

Pronunciation

  • (Received Pronunciation) IPA(key): /ˈæd͡ʒʊv(ə)nt/
  • (General American) enPR: 'ăj-ə-vənt, IPA(key): /ˈæd͡ʒəv(ə)nt/
  • Audio (General American):(file)
  • Hyphenation: ad‧juv‧ant

Adjective

adjuvant (comparative more adjuvant, superlative most adjuvant)

  1. (formal) Providing assistance or help; assistive, facilitative, helpful. [from 16th c.]
    Synonyms: assisting, auxiliary, complementary, contributory, helping, supporting
  2. (immunology) Enhancing the immune response to an antigen; also, containing a substance having such an effect.
  3. (medicine) Of a form of therapy or treatment: additional, supplementary; specifically (oncology), of a cancer treatment: given after removal of a primary tumour. [from 19th c.]
    • 2010, Siddhartha Mukherjee, “Halsted’s Ashes”, in The Emperor of all Maladies: A Biography of Cancer, New York, N.Y.: Scribner, →ISBN, page 219:
      Adjuvant chemotherapy, [Paul] Carbone conjectured, could be the surgeon's little helper. It would eradicate microscopic deposits of cancer left behind after surgery, thus extirpating any remnant reservoirs of malignancy in the body in early breast cancer— []

Derived terms

Translations

Noun

adjuvant (plural adjuvants)

  1. (formal) Someone or (more commonly) something that assists, facilitates, or helps; an aid, an assistant, a helper. [from 16th c.]
    Synonyms: accessory, attendant
    1. (agriculture) An additive (often a separate product) that enhances the efficacy of a pesticide, but has little or no pesticidal effect itself. [from mid 20th c.]
    2. (immunology) A substance enhancing the immune response to an antigen. [from 20th c.]
      • 1914 November, Frederick P. Gay, Edith J[ane] Claypole, “Specific Hyperleukocytosis: Studies in Typhoid Immunization”, in Archives of Internal Medicine[1], volume XIV, number 5, →DOI, →ISSN, →OCLC, pages 662–670:
        The well-known tropic action of immune serum as an adjuvant to phagocytosis suggested early in our studies that we might here be dealing with a similar phenomenon.
    3. (medicine) A form of therapy or treatment which is additional or supplementary to another, or which enhances the effectiveness of another. [from 18th c.]
    4. (pharmacology, archaic) An additive which aids or modifies the action of the principal ingredient of a drug. [from 19th c.]

Derived terms

Translations

References

  1. 1.0 1.1 Compare adjuvant, adj. and n.”, in OED Online , Oxford: Oxford University Press, September 2024; adjuvant, adj. and n.”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.

Further reading

French

Pronunciation

Adjective

adjuvant (feminine adjuvante, masculine plural adjuvants, feminine plural adjuvantes)

  1. adjuvant

Noun

adjuvant m (plural adjuvants)

  1. adjuvant

Further reading

Latin

Verb

adjuvant

  1. third-person plural present active indicative of adjuvō

Romanian

Etymology

Borrowed from French adjuvant or German Adjuvant.

Adjective

adjuvant m or n (feminine singular adjuvantă, masculine plural adjuvanți, feminine and neuter plural adjuvante)

  1. adjuvant

Declension

Declension of adjuvant
singular plural
masculine neuter feminine masculine neuter feminine
nominative-
accusative
indefinite adjuvant adjuvantă adjuvanți adjuvante
definite adjuvantul adjuvanta adjuvanții adjuvantele
genitive-
dative
indefinite adjuvant adjuvante adjuvanți adjuvante
definite adjuvantului adjuvantei adjuvanților adjuvantelor

Noun

adjuvant m (plural adjuvanți)

  1. adjuvant

Declension

Declension of adjuvant
singular plural
indefinite definite indefinite definite
nominative-accusative adjuvant adjuvantul adjuvanți adjuvanții
genitive-dative adjuvant adjuvantului adjuvanți adjuvanților
vocative adjuvantule adjuvanților