Definitions
1.nounSomeone who helps or facilitates; an assistant, a helper.
2.nounSomething that enhances the effectiveness of a medical treatment; a supplementary treatment.
3.nounAn additive (as in a drug) that aids or modifies the action of the principal ingredient.
4.noun(pesticide science) An additive (often a separate product) that enhances the efficacy of pesticide products, but has little or no pesticidal activity itself.
5.nounA substance enhancing the immune response to an antigen.