adjuvant

The story

1. French · derived fromadjuvant
2. Proto-Indo-European · derived from*h₁ewH-“to assist, help; to save”
3. Latin · learned borrowing fromadiuvant-
4. English todayadjuvant

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”)). 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).

First known use, by meaning

• from 16th c. Providing assistance or help; assistive, facilitative, helpful.
• from 19th c. Of a form of therapy or treatment: additional, supplementary; specifically (oncology), of a cancer treatment: given after removal of a primary tumour.
• from 16th c. An additive (often a separate product) that enhances the efficacy of a pesticide, but has little or no pesticidal effect itself.
• from 16th c. A substance enhancing the immune response to an antigen.
• from 16th c. A form of therapy or treatment which is additional or supplementary to another, or which enhances the effectiveness of another.
• from 16th c. An additive which aids or modifies the action of the principal ingredient of a drug.