An expert is someone who knows a ton about the subject at hand. The adjective form of expert describes someone or something that has that special knowledge. If you get expert instruction, that … One of my favorite things about ExpertVoice is learning about different companies, what products they offer & how they can benefit our members. My favorite company on EV is TaylorMade Golf.” I am so … EXPERT definition: a person who has special skill or knowledge in some particular field; specialist; authority. See examples of expert used in a sentence. a person with a high level of knowledge or skill relating to a particular subject or activity…. possessing special skill or knowledge. pertaining to or characteristic of an expert: expert advice.