milk-curdling enzyme, 1897, from rennet (n.1) + -in (2).

"inner membrane in the stomach of an unweaned calf or other animal," used for making cheese, etc.; also the mass of curdled milk found in the stomach, mid-15c., 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" (from PIE root *rei- "to run, flow"). Compare German rinnen "to run," gerinnen "to curdle." Hence, "anything used to curdle milk."

"make known by open declaration, publish, announce" (a decree, news, etc.), 1520s, from Latin promulgatus, past participle of promulgare "make publicly known, propose openly, publish," probably from pro "forth" (see pro-) + mulgere "to milk" (see milk (n.)), used metaphorically for "cause to emerge." In that case the word is "a picturesque farmers' term used originally of squeezing the milk from the udder" [L.R. Palmer, "The Latin Language"]. Related: Promulgated; promulgating. The earlier verb in English was promulge (late 15c.).

term of contempt for an effeminate, spiritless man, "one who is devoid of manliness," late 14c.; attested as a (fictional) surname mid-13c.; also applied in Middle English to the infant Christ. Literal sense "piece of bread soaked in milk" attested late 15c.; see milk (n.) + sop (n.).

1808, "establishment where milk is made into butter and cheese," from French crémerie, from crème (see cream (n.)).