1. (Science: zoology) 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.
The ophiuroids are also sometimes called starfishes. See brittle star, and ophiuroidea.
Synonym: sea star, five-finger, and stellerid.