The Collaborative International Dictionary of English v.0.48:

Frog \Frog\ (fr[o^]g), n. [AS. froggu, frocga a frog (in
   sensel); akin to D. vorsch, OHG. frosk, G. frosch, Icel.
   froskr, fraukr, Sw. & Dan. fr["o].]
   1. (Zool.) An amphibious animal of the genus Rana and
      related genera, of many species. Frogs swim rapidly, and
      take long leaps on land. Many of the species utter loud
      notes in the springtime.
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   Note: The edible frog of Europe (Rana esculenta) is
         extensively used as food; the American bullfrog (R.
         Catesbiana) is remarkable for its great size and loud
         voice.
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   2. [Perh. akin to E. fork, cf. frush frog of a horse.]
      (Anat.) The triangular prominence of the hoof, in the
      middle of the sole of the foot of the horse, and other
      animals; the fourchette.
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   3. (Railroads) A supporting plate having raised ribs that
      form continuations of the rails, to guide the wheels where
      one track branches from another or crosses it.
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   4. [Cf. fraco of wool or silk, L. floccus, E. frock.] An
      oblong cloak button, covered with netted thread, and
      fastening into a loop instead of a button hole.
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   5. The loop of the scabbard of a bayonet or sword.
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   Cross frog (Railroads), a frog adapted for tracks that
      cross at right angles.

   Frog cheese, a popular name for a large puffball.

   Frog eater, one who eats frogs; -- a term of contempt
      applied to a Frenchman by the vulgar class of English.

   Frog fly. (Zool.) See Frog hopper.

   Frog hopper (Zool.), a small, leaping, hemipterous insect
      living on plants. The larv[ae] are inclosed in a frothy
      liquid called cuckoo spit or frog spit.

   Frog lily (Bot.), the yellow water lily (Nuphar).

   Frog spit (Zool.), the frothy exudation of the frog
      hopper; -- called also frog spittle. See Cuckoo spit,
      under Cuckoo.
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