Webster's Revised Unabridged Dictionary · 1913

major league

major league , noun

(Sports) The most important league{2} in any sport (especially baseball); contrasted with minor league. Its teams are more competent, its members are paid more, and its games attract more interest and publicity, than those of a minor league.

major-league , adjective

1.
Of or pertaining to a major league; as, major-league football rules.
2.
Among the best or most important of its class; as, a major-league computer manufacturer.

Also: major league