/ren"it/ , n.
1. the lining membrane of the fourth stomach of a calf or of the stomach of certain other young animals.
2. the rennin-containing substance from the stomach of the calf.
3. a preparation or extract of the rennet membrane, used to curdle milk, as in making cheese, junket, etc.
[ 1400-50; late ME; cf. OE gerennan, OHG gerennen to coagulate; akin to RUN ]