bush league (adj.)youdaoicibaDictYouDict[bush league 词源字典]
"mean, petty, unprofessional," 1906, from baseball slang for the small-town baseball clubs below the minor league where talent was developed (by 1903), from bush (n.) in the slang sense of "rural, provincial," which originally was not a value judgment.[bush league etymology, bush league origin, 英语词源]