curd: [14] Curd began life as crud, a word which has survived in its own right. In the 15th century it underwent a process known as metathesis, by which the sounds r and u became transposed, producing curd. A derivative of this, dating from the 16th century, is curdle. The word’s ultimate ancestry is not known, although some consider that Gaelic gruth may be related. [curd etymology, curd origin, 英语词源]