Lewis & Short

altānus, i, m., a south-southwest wind, between the Africus and Libonotus, Vitr. 1, 6, 10, cf. Plin. 2, 43, 44, § 114 (acc. to Isid. Orig. 13, 11 and Serv. ad Verg. A. 7, 27, the sea winds were so called quod ab alto spirant).