Lewis Short
dextans (noun M) : contr. from de and sextans: as dempto sextante,Varr. L. L. 5, § 172 Müll.
* Ten twelfths of any thing (mostly post-Aug.; Cic. writes instead: pars dimidia et tertia, Fam. 13, 29, 4; cf.: remissis senio et trientibus,id. Sest. 25, 55), Varr. l. l.: jugeri,Col. 5, 1, 12: horae,Plin. 18, 32, 75, § 324: gradus neque crassiores dextante, neque tenuiores dodrante,Vitr. 3, 3: pro semisse dextans,Suet. Ner. 32.
Charlton T. Lewis, Charles Short, A Latin Dictionary