Definitions
1.AdjectiveExtraordinary capable or knowledgeable."I am expert at making a simple situation complex.; My cousin is an expert pianist."
2.AdjectiveCharacteristic of an expert."This problem requires expert knowledge."
3.AdjectiveProven, experienced, veteran.
4.NounA person with extensive knowledge or ability in a given subject."If an expert says it can't be done, get another expert. - David Ben-Gurion; We called in several experts on the subject, but they couldn't reach an agreement."
5.NounA player ranking just below master.
6.VerbTo have (something) reviewed or checked by an expert.