expert

expert,

n a person who has special skill or knowledge in a particular subject, such as a science or art, whether acquired by experience or study; a specialist.

expert system,

n a computer program that follows a logical pathway or algorithm to a conclusion in a manner that mimics what an expert in the field would follow.

expert testimony,

n the sworn statements of a person with special knowledge about a subject under consideration by a court of law.

expert witness,

n a person who has special knowledge of a subject about which a court requests testimony to educate the court and the jury in the subject under consideration.