Professional /(?)/

Pro·fes·sion·al

Professional

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

Professional

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