the lining membrane of the fourth stomach of a calf or of the stomach of certain other young animals.
the rennin-containing substance from the stomach of the calf.
a preparation or extract of the rennet membrane, used to curdle milk, as in making cheese, junket, etc.

Origin of rennet

1400–50; late Middle English; compare Old English gerennan, Old High German gerennen to coagulate; akin to run Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for rennet

Historical Examples of rennet

British Dictionary definitions for rennet



  1. the membrane lining the fourth stomach (abomasum) of a young calf
  2. the stomach of certain other young animals
a substance, containing the enzyme rennin, prepared esp from the stomachs of calves and used for curdling milk in making cheese and junket

Word Origin for rennet

C15: related to Old English gerinnan to curdle, run
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for rennet

"inner membrane of a calf's fourth stomach," c.1400, probably from an unrecorded Old English *rynet, related to gerennan "cause to run together," because it makes milk run or curdle; from Proto-Germanic *rannijanan, causative of *renwanan "to run" (see run (v.)). Cf. German rinnen "to run," gerinnen "to curdle."


variety of apple, 1560s, from French reinette, literally "little queen," diminutive of reine "queen," from Latin regina (see Regina).

Online Etymology Dictionary, © 2010 Douglas Harper