efficacious

the word efficacious has a direct lineage from latin, built upon the verb 'efficere', meaning 'to accomplish' or 'to bring about'. this verb itself is a compound of 'ex-' (meaning 'out' or 'thoroughly') and 'facere' (the prolific latin root meaning 'to make' or 'to do'). the adjective form 'efficax' entered english in the early 16th century, later refined to 'efficacious' with the addition of the '-ious' suffix, a common adjectival ending. thus, the literal sense of 'thoroughly making' or 'accomplishing out' evolved seamlessly into the modern abstract meaning of being capable of producing a desired effect.

Structure: ef (out, thoroughly) + fic (make, do) + ious (adjective suffix) ef- (variant of 'ex-'), from latin, meaning 'out' or 'thoroughly'. fic, from latin 'facere', meaning 'to make' or 'to do'. ious, a latin-derived adjective-forming suffix meaning 'full of' or 'characterized by'.