croupon

noun3

1. •
   A cowhide with the belly and neck removed.

   • The hot air is shut off and 2 pailfuls cold water added with ½ liter benzin per croupon[…] — 1913
2. •
   (no longer used) The croup of a horse or quadruped.
3. •
   (no longer used) The human buttocks.