1. noun
a) A person who belongs to a profession
I have learned that there is a person attached to a golf club called a professional. Find out who fills that post at the Green Meadow Club; invite the professional, urgently, to dine with us this evening.
b) A person who earns his living from a specified activity
2. adjective
a) Of, pertaining to, or in accordance with the (usually high) standards of a profession.
Wikipedia foundation.