\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.