Lewis & Short

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

Sextīlis, e, adj. [sextus], sixth, only with mensis, of the month of August: MENSE SEXTILI, S. C. ap. Macr. S. 1, 12 fin.: Sextili menso caminus, Hor. Ep. 1, 11, 19.
Hence, subst.: Sextīlis, is, m. (sc. mensis), the sixth (month); hence, the month of August, acc. to the old Roman reckoning (counting from March), afterwards called Augustus (v. h. v., and cf. Varr. L. L. 6, 4 fin.), Cic. Fam. 10, 26, 1: Sextilem totum mendax desideror, Hor. Ep. 1, 7, 2: Kalendae, of August, Liv. 3, 6; 6, 1 fin.: Nonae, Idus, id. 41, 16.

Sextĭlĭus, i, m.; Sextĭlĭa, ae, f., the name of a Roman gens: C. Sextilius Rufus, Cass. ap. Cic. Ep. Fam. 12, 13, 4; 13, 48 tit.: Sextilia, Suet. Vit. 3; Tac. H. 2, 64.
Hence, Sextĭlĭānus, a, um, adj., of or named from a Sextilius: pira, Cloat. ap. Macr. S. 2, 15 fin.