Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dextans, antis, 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.