Obs. exc. dial. [app. identical with ME. erne (repr. both OE. iernan, metathetic var. of rinnan, RUN, and the causative ærnan = ręnnan): in OE. the prefix-vbs. ʓe-rinnan, ʓe-ręnnan, occur in the senses ‘curdle, cause to curdle’; the pple. ʓeurnen ‘curdled’ is found in Leechdoms II. 230, 272, III. 278.] intr. To curdle. Also trans. To curdle (milk), esp. for making into cheese.
1674. Ray, N. C. Wds., 16. To Earn: to run as cheese doth…. Var. Dialect.
1724. Ramsay, Tea-t. Misc. (1733), I. 86. The kirn’s to kirn, and milk to earn.
1769. Mrs. Raffald, Eng. Housekpr. (1776), 250. When it [new milk] is ready to boil put in a quart of good cream, earn it.
1877. E. Peacock, N.-W. Linc. Gloss. (E. D. S.), Earn, to curdle with rennet.
