a. (Zool.) Of or pertaining to the Ostracoidea (now Ostracoda). -- n. One of the Ostracoidea (now Ostracoda). [ 1913 Webster +PJC ]

‖n. pl. [ NL., fr. Gr. 'o`strakon shell of a testacean + -oid. ] (Zool.) An order of Entomostraca possessing hard bivalve shells. They are of small size, and swim freely about. Now usually written Ostracoda. [ archaic ] [ 1913 Webster +PJC ]