I. ˈa-jə-vənt adjective
Etymology: French or Latin; French, from Latin adjuvant-, adjuvans, present participle of adjuvare to aid — more at aid
Date: 1574
1. : serving to aid or contribute : auxiliary
2. : assisting in the prevention, amelioration, or cure of disease
adjuvant chemotherapy following surgery
II. noun
Date: 1609
: one that helps or facilitates: as
a. : an ingredient (as in a prescription or a solution) that modifies the action of the principal ingredient
b. : something (as a drug or method) that enhances the effectiveness of medical treatment
used chemotherapy as an adjuvant to surgery
c. : a substance (as one added to a vaccine) enhancing the immune response to an antigen