marsouin

porpoise

Occurring in a 1086 Medieval Latin translation of the Domesday Book, from Old English mereswīn (“porpoise”), but probably reborrowed from another Germanic source cognate to the Old English word, from Old Frankish *mariswīn, Middle Dutch meerswijn, or Old Norse marsvín (“dolphin”), all ultimately from Proto-Germanic *mariswīną (“dolphin, porpoise”). More at English mereswine. Cf. also the Old French porpeis.