rump vs sit upon

rump

noun
  • The buttocks. 

  • A cut of meat from the rump of an animal. 

  • The hindquarters of a four-legged mammal, not including its legs 

  • A remnant, as in Rump Parliament. 

verb
  • To turn one's back on, to show one's (clothed) backside to, as a sign of disrespect. 

  • To fuck. (Compare bum (verb).) 

  • To cheat. 

  • To ramble; to move (or talk) aimlessly. 

  • To move (someone or something) around. 

sit upon

noun
  • buttocks, bottom 

  • small, portable cushion for sitting on 

verb
  • Synonym of sit on (“block, suppress, hold back”) 

How often have the words rump and sit upon occurred in a corpus of books? (source: Google Ngram Viewer )