Added 9 October 2026 effectiveness /ɪˈfɛk.tɪv.nɪs/ noun Categories: Describing WordsEveryday Words noun ! Definition from WordNet 3.1, Princeton University. Pronunciation from Wiktionary, via Kaikki.org. More about effectiveness at Wordnik → Where our words come from → Power to be effective; the quality of being able to bring about an effect. Capacity to produce strong physiological or chemical effects. the toxin's potency Related Words: effectualityeffectualnesspotencystrengthefficacyefficaciouseffectivelyusefulnessproductivityexpediencycapabilityfunctioning Back to today's word