crupper
noun
crup·per ˈkrə-pər 
ˈkru̇-
ˈkru̇- 1
: a leather loop passing under a horse's tail and buckled to the saddle
2
: croup entry 1
broadly : buttocks
Word History
Etymology
Middle English croper, croppere, borrowed from Anglo-French croupere (continental Old French croupiere) from croupe croup entry 1 + -ere -er entry 2
First Known Use
14th century, in the meaning defined at sense 1