Lewis & Short

sīnum, i, n. (masc. collat. form sīnus, Plaut. Curc. 1, 1, 82; id. Rud. 5, 2, 31; for the form of the abl., sinu, Varr. ap. Non. 547, 23, we should perh. substitute sino; cf. Prisc. p. 714 P.) [1. sinus], a large, round drinking-vessel with swelling sides (like our bowls), esp. for wine (cf. Cic. Fragm. ap. Schol. Veron. ad Verg. E. 7, 33), Varr. L. L. 5, § 123 Müll.; id. ap. Non. 547, 23; Plaut. Curc. 1, 1, 75; 1, 1, 82; id. Rud. 5, 2, 32; Atta ap. Serv. Verg. E. 7, 33; Valgius ap. Philarg. Verg. G. 3, 177; Col. 7, 8, 2 al.; cf. Becker, Gallus, 3, p. 225 (2d edit.).