pro-am (adj.)

1784, "one who has a taste for some art, study, or pursuit, but does not practice it," from French amateur "one who loves, lover" (16c., restored from Old French ameour), from Latin amatorem (nominative amator) "lover, friend," agent noun from amatus, past participle of amare "to love" (see Amy).

The meaning "one who cultivates and participates (in something) but does not pursue it professionally or with an eye to gain" (as opposed to professional) is from 1786; often with disparaging suggestions of "dabbler, dilettante," but not in athletics, where the disparagement shaded the professional, at least formerly. As an adjective, by 1838.

mid-15c., profeshinalle, in reference to the profession of religious orders; see profession. By 1747 of careers, "pertaining to or appropriate to a profession or calling" (especially of the skilled or learned trades from c. 1793);  In sports and amusements, "undertaken or engaged in for money" (opposed to amateur), by 1846. Related: Professionally.