sea-horse (n.)youdaoicibaDictYouDict[sea-horse 词源字典]
late 15c., "walrus," from sea + horse (n.); also see walrus. Also in heraldry as a fabulous animal with the foreparts of a horse and the tail of a fish. Main modern sense in zoology is attested from 1580s.[sea-horse etymology, sea-horse origin, 英语词源]