Starfish

Full definition of starfish

(plural starfishes or starfish)

Any of various asteroids or other echinoderms (not in fact fish) with usually five arms, many of which eat bivalves or corals by everting their stomach.
(vulgar, slang, usually in translations of Japanese pornography) an anus. See also chocolate starfish.
(obsolete) Any many-armed or tentacled sea invertebrate, whether cnidarian, echinoderm, or cephalopod.

1755, Erik Pontoppidan, trans. Isaac Kimbler, Explanation of the Plate of Uncommon Star Fish, Extracted from the Natural History of NorwayBut the largest of the star-fish kind is that sea monster called kruken, kraken or krabben. ... As this enormous sea-animal in all probability may be reckoned of the polype, or of the star-fish, kind, it seems that the parts which are seen rising at its pleasure, and are called arms, are properly the tentacula, or feeding instruments, called horns as well as arms.