What is "rennet stomach"

Rennet \Ren"net\, n. [AS. rinnan, rennan, to run, cf. gerinnan to curdle, coagulate. [root]1

1. See Run, v.] 1. The inner, or mucous, membrane of the fourth stomach of the calf, or other young ruminant.

2. an infusion or preparation of the calf stomach lining, used for coagulating milk. The active principle in this coagulating action is the enzyme rennin. [Written also runnet.]

   Cheese rennet. (Bot.) See under Cheese.

   Rennet ferment (Physiol. Chem.), the enzyme rennin, present in rennet and in variable quantity in the gastric juice of most animals, which has the power of curdling milk. The enzyme presumably acts by changing the casein of milk from a soluble to an insoluble form.

   Rennet stomach (Anat.), the fourth stomach, or abomasum, of ruminants.

n. The fourth stomach of a ruminant, the abomasum.