Pronunciation: (hag'fish"),[key] —n., —pl.(esp. collectively)-fish,(esp. referring to two or more kinds or species)-fish•es. any eellike, marine cyclostome of the order Myxiniformes, having undeveloped eyes, a barbel-rimmed, circular mouth, and horny teeth for boring into the flesh of fishes to feed on their interior parts. See illus. in next column.