Source : Webster's Revised Unabridged Dictionary (1913)

Physalia \Phy*sa"li*a\, n. [NL., fr. Gr. ? a bladder, fr. ? a
   bellows.] (Zo["o]l.)
   A genus of large oceanic Siphonophora which includes the
   Portuguese man-of-war.

   Note: It has a large air sac, or float, with a sail-like
         crest on its upper side. Numerous zooids of different
         kinds are attached to the under side of the float. Some
         of the zooids have very long tentacles; some have a
         mouth and digest food; others produce gonophores. The
         American species ({Physalia arethusa}) is brilliantly
         colored, the float being pink or purple, and bright
         blue; the zooids blue. It is noted for its virulent
         stinging powers, as well as for its beautiful colors,
         graceful motions, and its ability to sail to windward.

Source : WordNet®

Physalia
     n : Portuguese man-of-war [syn: {genus Physalia}]