Lewis & Short

† ostrĕa, ae, f., and (rarely) ostrĕum, i, n., = ὄστρεον, an oyster, mussel, sea-snail (class.).

        1. (α) Form ostrea, Enn. Heduph. 2 (p. 166 Vahl.); Lucil. ap. Non. 216, 6; Afran.; Turp. and Varr. ib.; Plaut. Rud. 2, 1, 8; Cic. Fragm. ap. Non. 216, 14: ostrearum vivaria, Plin. 9, 54, 79, § 168.
        2. (β) Form ostreum: luna alit ostrea, Lucil. ap. Gell. 20, 8, 4; id. ap. Non. 216, 16; Varr. ib. 20: ostrea Circeis, Miseno oriuntur echini, Hor. S. 2, 4, 33; Ov. F. 6, 174; Juv. 4, 142.
          In sing. collect.: ostrei testas siccas tundere, Pall. 1, 41, 3.