Lewis & Short

Ŏăsis, is, f., = Ὄασις [orig. a Coptic word], an inhabited spot, a fertile piece of land in the Libyan desert, an oasis; esp. the great oasis in Upper Egypt, to which criminals were banished by the emperors, Cod. Just. 9, 47, 26; Dig. 48, 22, 7, § 5.
Hence,

  1. A. Ŏăsēnus, a, um, adj., of or belonging to Oasis: Oasena deportatio, Cod. Th. 9, 32.
  2. B. Ŏăsītes, ae, m., adj., of or belonging to Oasis, Oasite: Oasitae nomi, Plin. 5, 9, 9, § 50.