Etymology

From Proto-Germanic *mariswīną ‎(“dolphin, porpoise”), from Proto-Germanic *mari ‎(“sea”) + Proto-Germanic *swīną ‎(“swine, pig”). Akin to Old High German merisuīn "dolphin, porpoise" (German Meerschwein "dolphin"), Old Norse marsvín ‎(“dolphin, sea-pig”). More at mere, swine.