Cyathus, ponderis genus. Plin. cyathus pendet per se drachmas decem. Ad cyathos stare vel esse. Suet. To attend on ones cup. Cyathus, Genus quoddam mensuræ. Col. The xii parte of Sextarius, that is ounces measure. After phisitions accõting 18 ounces to Sextarius. it is but an ounce and a halse.
Lewis and Short: Latin dictionary
căthus, i, m., = ku/aqos, a small ladle for transferring the wine from the mixing-bowl (crater) to the drinking-cup (cf. Becker, Gall. 3, p. 221). I. Prop., Varr. L. L. 5, 124 Müll.; Plaut. Stich. 5, 4, 24; id. Ps. 4, 2, 2; Hor. S. 1, 6, 117; Juv. 9, 47; Suet. Caes. 49 al.—II. As a measure, both dry and liquid (particularly for wine), the twelfth part of a sextarius, Hor. C. 3, 8, 13; 3, 19, 12; Plin. 14, 9, 11, 85; or ten Greek drachmæ, Plin. 21, 34, 109, 185; cf. Rhemn. Fann. Pond. 80.