athlete (n.)

early 15c. (Chauliac), "competitor in athletic games and contests," from Latin athleta "a wrestler, athlete, combatant in public games," from Greek athlētēs "prizefighter, contestant in the games," agent noun from athlein "to contest for a prize," which from athlos "a contest," especially for a prize (its neuter form, athlon, meant "the prize of a contest"), a word of unknown origin.

Until mid-18c. it was usually in English in Latin form. Old English had plegmann "play-man." The meaning "one trained in exercises of agility and strength" is by 1827. Athlete's foot is recorded by 1928, for an ailment that has been around much longer.