Source : Webster's Revised Unabridged Dictionary (1913)

Oasis \O"as*is\ ([=o]"[.a]*s[i^]s or [-o]*[=a]"s[i^]s; 277), n.;
   pl. {Oases} (-s[=e]z). [L., fr. Gr. 'o`asis; cf. Copt.
   ouahe.]
   A fertile or green spot in a waste or desert, esp. in a sandy
   desert.

         My one oasis in the dust and drouth Of city life.
                                                  --Tennyson.

Source : WordNet®

oasis
     n 1: a fertile tract in a desert (where the water table
          approaches the surface)
     2: a shelter serving as a place of safety or sanctuary [syn: {haven}]
     [also: {oases} (pl)]

oases
     See {oasis}