efficacious
UK /ˌɛf.ɪˈkeɪ.ʃəs/ · US /ˌɛf.əˈkeɪ.ʃəs/ adjective
- adjective (formal) Effective; possessing efficacy. “This medicine is efficacious.”
Synonyms
Antonyms
Etymology
From Old French efficacieux (whence -acious), from Latin efficāx (“efficacious”) + -ous, from efficere (“to effect, to accomplish”); see effect.
Webster’s 1913
- adjective Possessing the quality of being effective; productive of, or powerful to produce, the effect intended; as, an efficacious law.
Etymology [L. eficax, -acis, fr. efficere. See Effect, n.]
Sources: Wiktionary · WordNet 3.0 · Webster’s 1913 — from the Wiktionary entry “efficacious”, CC BY-SA 4.0. Details