Occurs only in connection with the sixth plague of Egypt (Ex. 9:9, 10). In Deut. 28:27, 35, it is called “the botch of Egypt.” It seems to have been the fearful disease of black leprosy, a kind of elephantiasis, producing burning ulcers.
Easton’s Bible Dictionary
Blains
Easton’s Bible Dictionary (1897), public domain. Text via Theographic Bible Metadata, CC BY-SA 4.0.