The Collaborative International Dictionary of English v.0.48:

Frigate \Frig"ate\, n. [F. fr['e]gate, It. fregata, prob.
   contracted fr. L. fabricata something constructed or built.
   See Fabricate.]
   1. Originally, a vessel of the Mediterranean propelled by
      sails and by oars. The French, about 1650, transferred the
      name to larger vessels, and by 1750 it had been
      appropriated for a class of war vessels intermediate
      between corvettes and ships of the line. Frigates, from
      about 1750 to 1850, had one full battery deck and, often,
      a spar deck with a lighter battery. They carried sometimes
      as many as fifty guns. After the application of steam to
      navigation steam frigates of largely increased size and
      power were built, and formed the main part of the navies
      of the world till about 1870, when the introduction of
      ironclads superseded them. [Formerly spelled frigat and
      friggot.]
      [1913 Webster]

   2. Any small vessel on the water. [Obs.] --Spenser.
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   Frigate bird (Zool.), a web-footed rapacious bird, of the
      genus Fregata; -- called also man-of-war bird, and
      frigate pelican. Two species are known; that of the
      Southern United States and West Indies is F. aquila.
      They are remarkable for their long wings and powerful
      flight. Their food consists of fish which they obtain by
      robbing gulls, terns, and other birds, of their prey. They
      are related to the pelicans.

   Frigate mackerel (Zool.), an oceanic fish (Auxis Rochei)
      of little or no value as food, often very abundant off the
      coast of the United States.

   Frigate pelican. (Zool.) Same as Frigate bird.
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The Collaborative International Dictionary of English v.0.48:

Mackerel \Mack`er*el\, n. [OF. maquerel, F. maquereau (LL.
   macarellus), prob. for maclereau, fr. L. macula a spot, in
   allusion to the markings on the fish. See Mail armor.]
   (Zool.)
   Any species of the genus Scomber of the family
   Scombridae, and of several related genera. They are finely
   formed and very active oceanic fishes. Most of them are
   highly prized for food.
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   Note: The common mackerel (Scomber scombrus), which
         inhabits both sides of the North Atlantic, is one of
         the most important food fishes. It is mottled with
         green and blue. The Spanish mackerel (Scomberomorus
         maculatus), of the American coast, is covered with
         bright yellow circular spots.
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   Bull mackerel, Chub mackerel. (Zool.) See under Chub.


   Frigate mackerel. See under Frigate.

   Horse mackerel . See under Horse.

   Mackerel bird (Zool.), the wryneck; -- so called because it
      arrives in England at the time when mackerel are in
      season.

   Mackerel cock (Zool.), the Manx shearwater; -- so called
      because it precedes the appearance of the mackerel on the
      east coast of Ireland.

   Mackerel guide. (Zool.) See Garfish
   (a) .

   Mackerel gull (Zool.) any one of several species of gull
      which feed upon or follow mackerel, as the kittiwake.

   Mackerel midge (Zool.), a very small oceanic gadoid fish of
      the North Atlantic. It is about an inch and a half long
      and has four barbels on the upper jaw. It is now
      considered the young of the genus Onos, or Motella.

   Mackerel plow, an instrument for creasing the sides of lean
      mackerel to improve their appearance. --Knight.

   Mackerel shark (Zool.), the porbeagle.

   Mackerel sky, or Mackerel-back sky, a sky flecked with
      small white clouds; a cirro-cumulus. See Cloud.
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            Mackerel sky and mare's-tails
            Make tall ships carry low sails.      --Old Rhyme.
      [1913 Webster] mackerel scad