'Sea star' definitions:

Definition of 'sea star'

noun

Echinoderms characterized by five arms extending from a central disk [syn: starfish, sea star]

From: GCIDE

From: GCIDE

Starfish \Star"fish`\ (-f[i^]sh`), n.
1. (Zool.) Any one of numerous species of echinoderms belonging to the class Asterioidea, in which the body is star-shaped and usually has five rays, though the number of rays varies from five to forty or more. The rays are often long, but are sometimes so short as to appear only as angles to the disklike body. Called also sea star, five-finger, and stellerid. [1913 Webster]
Note: The ophiuroids are also sometimes called starfishes. See Brittle star, and Ophiuroidea. [1913 Webster]
2. (Zool.) The dollar fish, or butterfish. [1913 Webster]