abomasum

noun2

1. •
   The fourth digestive compartment of the stomach of a cow or other ruminant, after the omasum;

   • Traditionally, coagulation of the milk for Feta cheese manufacture was achieved using rennet produced by cheesemakers themselves from the abomasa of lambs and kids slaughtered before weaning. — 1996
2. •
   the lining of said compartment, considered as a foodstuff.