If you are proficient or adept at something you are skillful—perhaps even expert. Proficient, adept, skillful, and expert are all synonyms, but subtle differences can be discerned between these terms as well. Proficient usually describes pure ability that comes from training and practice ("a proficient writer"). Adept suggests an innate ability as well as a learned skill ("an adept card player"). Skillful suggests being very able at a particular task ("a skillful surgeon"). Expert suggests having a thorough knowledge of a subject as well as being very skillful at working in it ("expert in the martial arts").

Comparing Efficient, Effective, and Proficient

These three words cover some overlapping territory.

Efficient most often describes what is capable of producing desired results without wasting materials, time, or energy. While the word can be applied to both people and things, it is far more commonly applied to things, such as machines, systems, processes, and organizations. The focus of the word is on how little is wasted or lost while the desired results are produced.

Effective typically describes things—such as policies, treatments, arguments, and techniques—that do what they are intended to do. People can also be described as effective when they accomplish what they set out to accomplish, but the word is far more often applied to things.

Proficient typically describes people, and it often is followed by the preposition at. If you are proficient at something, you are very good at it. You are, in fact, so good at doing it that you are unusually efficient when you do it. One can also be proficient in something, such as a language.