What does bush league mean?

bush league meaning in Etymology Dictionary

"mean, petty, unprofessional," 1906, from baseball slang the small-town baseball groups below the minor league in which skill was developed (by 1903), from bush (n.) into the slang sense of "rural, provincial," which originally was not a price view.

bush league meaning in General Dictionary

a league of teams that don't are part of an important league (especially baseball)