/ Dictionary / Index E effector: Meaning and Definition of Find definitions for: ef•fec•tor Pronunciation: (i-fek'tur), [key] — n. a person or thing that effects. an organ or cell that carries out a response to a nerve impulse. a substance, as a hormone, that increases or decreases the activity of an enzyme. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: effector (Thesaurus) effective sound pressure effects Related Content Daily Word Quiz: transient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language