[ef-i-key-shuh
s] 
| capable of having the desired result or effect; effective as a means, measure, remedy, etc.: The medicine is efficacious in stopping a cough. |
| ef·fi·ca·cious (ěf'ĭ-kā'shəs) adj. Producing or capable of producing a desired effect. See Synonyms at effective. [From Latin efficāx, efficāc-, from efficere, to effect; see effect.] ef'fi·ca'cious·ly adv., ef'fi·ca'cious·ness n. |