adjuvant

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 adjective sense 3 (“of a form of therapy or treatment: additional, supplementary”) and noun 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).