Te·thys /ˈtiθəs/
  土衛三; 古地中海
  Te·thys n.  Zool. A genus of a large naked mollusks having a very large, broad, fringed cephalic disk, and branched dorsal gills. Some of the species become a foot long and are brilliantly colored.
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  Tethys
       n 1: (Greek mythology) a Titaness and sea goddess; wife of
            Oceanus
       2: type genus of the family Aplysiidae [syn: Aplysia, genus
          Aplysia, genus Tethus]