major-league

/M EY1 JH ER0 L IY1 G/
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.

    โ€œCalatrava is a major league architect.โ€

  3. 3

    Serious, high-level; significant

    โ€œBill accidentally faxed sensitive documents to our competitors, and such a major league mess-up could only be dealt with by firing Bill.โ€

Source: https://en.wiktionary.org/wiki/major%20league, https://en.wiktionary.org/wiki/major-league