1250-1300;Middle Englishranclen < Middle Frenchrancler,Old Frenchraoncler, variant of draoncler to fester, derivative of draoncle a sore < Late Latindracunculus small serpent, diminutive of Latindracō serpent; see dragon, carbuncle
c.1320, from O.Fr. rancler, from draoncle "abscess, festering sore," from L. dracunculus "little snake," dim. of draco (gen. draconis) "serpent, dragon." The notion is of an ulcer caused by a snake's bite.