Source : Webster's Revised Unabridged Dictionary (1913)

Proficient \Pro*fi"cient\, n. [L. proficiens, -entis, p. pr. of
   proficere to go forward, make progress; pro forward + facere
   to make. See {Fact}, and cf. {Profit}, (?)]
   One who has made considerable advances in any business, art,
   science, or branch of learning; an expert; an adept; as,
   proficient in a trade; a proficient in mathematics, music,
   etc.

Proficient \Pro*fi"cient\, a.
   Well advanced in any branch of knowledge or skill; possessed
   of considerable acquirements; well-skilled; versed; adept,

Source : WordNet®

proficient
     adj : having or showing knowledge and skill and aptitude; "adept
           in handicrafts"; "an adept juggler"; "an expert job";
           "a good mechanic"; "a practiced marksman"; "a
           proficient engineer"; "a lesser-known but no less
           skillful composer"; "the effect was achieved by
           skillful retouching" [syn: {adept}, {expert}, {good}, {practiced},
            {skillful}, {skilful}]