Decussis, huius decussis, m. g. Ten whole partes, or ten Asses, Ten pound waight. Also peeces equally cut. It is vsed of Vitruuius for the number of ten. Also the forme of any thing representing the letter x, which parted in the middle maketh an other figure called Quincunx. v.
Decussus, huius decussus, m. g. Actus ipse decutiendi. Plinius. A striking or shaking off.
Decutio, décutis, pen. corr. decussi, decussum. decútere, ex De & Quatio, quatis, compositum. To strike or shake off.
Lewis and Short: Latin dictionary
dĕcussis, is (also decus, i, a mutilated form used by the Agrimensores, p. 231, 243, and 265, ed. Goes.), m. [decem-as]. I.The number ten: ex singularibus rebus, quae mona/des apud Graecos dicuntur perficitur decussis, Vitr. 3, 1 (cf. the art. as, no. I.).—Hence, decussis sexis, or in one word, dĕcussissexis, the number sixteen, Vitr. 3, 1, 8.—B. Because the Roman numeral sign for ten was X, decussis was used to denote the intersection of two lines in the form of a cross: regula figitur in primo decussis puncto, Vitr. 10, 11; Plin. 18, 34, 77, 331. Cf. decusso and its derivatives.—II. (Acc. to as, no. II.) Ten asses; as a Roman coin, a ten-as piece, Varr. L. L. 5, 170; Lucil. ib. 9, 81 Müll.; Stat. Silv. 4, 9, 9; Fest. p. 237, 20 Müll.