Source : Webster's Revised Unabridged Dictionary (1913)

Delphinus \Del*phi"nus\, n. [L., a dolphin, fr. Gr. delfi`s,
   delfi`n.]
   1. (Zo["o]l.) A genus of Cetacea, including the dolphin. See
      {Dolphin}, 1.

   2. (Astron.) The Dolphin, a constellation near the equator
      and east of Aquila.

Porpoise \Por"poise\, n. [OE. porpeys, OF. porpeis, literally,
   hog fish, from L. porcus swine + piscis fish. See {Pork}, and
   {Fish}.]
   1. (Zo["o]l.) Any small cetacean of the genus {Phoc[ae]na},
      especially {P. communis}, or {P. phoc[ae]na}, of Europe,
      and the closely allied American species ({P. Americana}).
      The color is dusky or blackish above, paler beneath. They
      are closely allied to the dolphins, but have a shorter
      snout. Called also {harbor porpoise}, {herring hag},
      {puffing pig}, and {snuffer}.

   2. (Zo["o]l.) A true dolphin ({Delphinus}); -- often so
      called by sailors.

   {Skunk porpoise}, or {Bay porpoise} (Zo["o]l.), a North
      American porpoise ({Lagenorhynchus acutus}), larger than
      the common species, and with broad stripes of white and
      yellow on the sides. See Illustration in Appendix.

Source : WordNet®

Delphinus
     n 1: a constellation in the northern hemisphere near Pegasus and
          Aquila
     2: type genus of the Delphinidae [syn: {genus Delphinus}]