/ Thesaurus / E Synonyms of effectiveness Find synonyms for: Noun1. effectiveness, effectivity, effectualness, effectuality, power, powerfulnessusage: power to be effective; the quality of being able to bring about an effect2. potency, effectiveness, strength, power, powerfulnessusage: capacity to produce strong physiological or chemical effects; "the toxin's potency"; "the strength of the drinks"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: languid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language