Entry 2 senses · 2 variants Webster, 1913 Clabber · Clab·ber · IPA /ˈklæb.ə(ɹ)/ n. v. i. 01 n. Milk curdled so as to become thick. 1. Milk curdled so as to become thick. 02 v. i. To become clabber; to lopper. 1. To become clabber; to lopper.