a person who has special skill or knowledge in some particular field; specialist; authority

a language expert.

Military .

the highest rating in rifle marksmanship, above that of marksman and sharpshooter.

a person who has achieved such a rating.

possessing special skill or knowledge; trained by practice; skillful or skilled (often fol. by in or at )

an expert driver; to be expert at driving a car.

pertaining to, coming from, or characteristic of an expert

expert work; expert advice.

to act as an expert for.

noun

adeptness , art , command , craft , expertise , knack , mastery , proficiency , skill , technique