major league

Short definition from Wiktionary

Noun

1. 1
   An association of sports teams which plays at the highest skill level of its sport, especially Major League Baseball.
2. 2
   The highest level of competition in a field of endeavor.

Adjective

1. 1
   Of or pertaining to a major sports league; belonging to the professional level of a sport, such as US baseball.
2. 2
   Analogous in importance to a major league sports team.
3. 3
   Serious, high-level; significant
4. 4
   Alternative form of major league.