Professional

Part of speech: noun (n.)

A person who prosecutes anything professionally, or for a livelihood, and not in the character of an amateur; a professional worker.

Part of speech: adjective (a.)

1. Of or pertaining to a profession, or calling; conforming to the rules or standards of a profession; following a profession; as, professional knowledge; professional conduct. "Pride, not personal, but professional." Macaulay. "A professional sneerer." De Quincey.

2. Engaged in by professionals; as, a professional race; -- opposed to amateur.