1. An inflammatory swelling or sore; a bulla, pustule, or blister. Blotches and blains must all his flesh emboss. (Milton)
2. (Science: veterinary) a bladder growing on the root of the tongue of a horse, against the windpipe, and stopping the breath.
Origin: oe. Blein, bleyn, as. Blgen; akin to dan. Blegn, D. Blein; perh. Fr. The same root as E. Bladder. See bladder.