adjuvant UK /ˈæd͡ʒʊv(ə)nt/US /ˈæd͡ʒəv(ə)nt/noun 5adjective 3forms 3 noun5 •An additive (often a separate product) that enhances the efficacy of a pesticide, but has little or no pesticidal effect itself. •A substance enhancing the immune response to an antigen.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. — 1914 •A form of therapy or treatment which is additional or supplementary to another, or which enhances the effectiveness of another. •(formal) Someone or (more commonly) something that assists, facilitates, or helps; an aid, an assistant, a helper. •(formal, no longer used) An additive which aids or modifies the action of the principal ingredient of a drug. adjective3 •Enhancing the immune response to an antigen; also, containing a substance having such an effect. •Of a form of therapy or treatment: additional, supplementary; specifically (oncology), of a cancer treatment: given after removal of a primary tumour. •(formal) Providing assistance or help; assistive, facilitative, helpful. formsadjuvants · more adjuvant · most adjuvant