bush league vs monotonous

bush league

adj
  • Amateurish, unprofessional, unpolished, juvenile. 

  • Of inferior quality. 

noun
  • A professional sports association at the lower levels of minor league organization. 

  • A low-ranking or inferior level among groups, professions, organizations, etc. 

monotonous

adj
  • Tedious, repetitious, or lacking in variety. 

  • Having an unvarying pitch or tone. 

How often have the words bush league and monotonous occurred in a corpus of books? (source: Google Ngram Viewer )