caboose vs crupper

caboose

noun
  • buttocks 

  • The person or team in last place. 

  • A youngest child who is born after a long gap in time. 

  • A small sand-filled container used as an oven on board ship. 

  • The last car on a freight train, having cooking and sleeping facilities for the crew; a guard’s van. 

crupper

noun
  • The buttocks or rump, especially of a horse. 

  • A strap, looped under a horse's tail, used to stop a saddle from slipping. 

  • A piece of armour covering the hindquarters/buttocks of a horse. 

verb
  • To fit with a crupper; to place a crupper upon. 

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