\Ren"net\ (r?n"n?t), n. [F. rainette, reinette, perhaps
fr. raine a tree frog, L. rana, because it is spotted like
this kind of frog. Cf. {Ranunculus}.] (Bot.)
A name of many different kinds of apples. Cf. {Reinette}.
--Mortimer.

\Ren"net\, n. [AS. rinnan, rennan, to run, cf. gerinnan
to curdle, coagulate. [root]11. See {Run}, v.]
The inner, or mucous, membrane of the fourth stomach of the
calf, or other young ruminant; also, an infusion or
preparation of it, used for coagulating milk. [Written also
{runnet}.]
{Cheese rennet}. (Bot.) See under {Cheese}.
{Rennet ferment} (Physiol. Chem.), a ferment, present in
   rennet and in variable quantity in the gastric juice of
   most animals, which has the power of curdling milk. The
   ferment 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.