efficacious
adjective/ˌefɪˈkeɪʃəs/
/ˌefɪˈkeɪʃəs/
(formal)- (of things, not of people) producing the result that was wanted or intended synonym effective
- They hope the new drug will prove especially efficacious in the relief of pain.
Word Originearly 16th cent.: from Latin efficax, efficac- (from efficere ‘accomplish’, from ex- ‘out, thoroughly’ + facere ‘do, make’) + -ious.Definitions on the go
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efficacious