additive

¹ad·di·tive

adj \ˈad-ət-iv\

Definition of ADDITIVE

: having or relating to a value or effect that is the sum of individual values or effects: as a : relating to the sum of the pharmacological responses produced by the concurrent administration of two or more drugs capable of producing the same kind of effect b : having a genetic effect that is the sum of the individual effects

—ad·di·tive·ly adverb

—ad·di·tiv·i·ty \ˌad-ə-ˈtiv-ət-ē\ noun, plural ad·di·tiv·i·ties