Pertaining or appropriate to a profession or calling: as, professional studies; professional skill.
Engaged in a profession; being such by profession.
Undertaken or engaged in for money or as a means of subsistence: opposed to amateur: said of sports and amusements: as, a professional base-ball match; a professional performance of a play.
noun.
One who regularly pursues any profession or art.
noun.
Specifically, a person who makes his living by an art, game, or sport in which amateurs are accustomed to engage for amusement or recreation.