The Oxford Thesaurus An A-Z Dictionary of Synonyms - expertn.

1) authority, professional, specialist, scholar, master, connoisseur, pundit, Colloq wizard, whiz, pro, ace, Brit dab hand, boffin, Slang US maven or mavin: We rely on experts to verify the age of works of art. --adj. 2) skilful, skilled, trained, knowledgeable, learned, experienced, practised, qualified, adept, proficient, accomplished, au fait, adroit, dexterous, polished, finished, masterful, masterly, first-rate, excellent, superb, wonderful, superior, champion(ship) , A-one, A-1, virtuoso, Colloq top-notch, Brit whizzo, wizard, US crackerjack, crack: Davis is an expert snooker player.