sea lion /ˈsiː ˈlaɪən/ noun4 •A pinniped of most genera in the family Otariidae (the eared seals).But Sophia's mother was not the woman to brook defiance. After a few moments' vain remonstrance her husband complied. His manner and appearance were suggestive of a satiated sea-lion. — 1921 •A monster consisting of the upper part of a lion combined with the tail of a fish (a lion marined). •(US, slang) A cow or bull transported by steamer from the ports of Texas. •(US, slang) A steamer transporting cattle from the ports of Texas. formssea lions