The Collaborative International Dictionary of English v.0.48:

Colt \Colt\ (k[=o]lt; 110), n. [OE. colt a young horse, ass, or
   camel, AS. colt; cf. dial. Sw. kullt a boy, lad.]
   1. The young of the equine genus or horse kind of animals; --
      sometimes distinctively applied to the male, filly being
      the female. Cf. Foal.
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   Note: In sporting circles it is usual to reckon the age of
         colts from some arbitrary date, as from January 1, or
         May 1, next preceding the birth of the animal.
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   2. A young, foolish fellow. --Shak.
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   3. A short knotted rope formerly used as an instrument of
      punishment in the navy. --Ham. Nav. Encyc.
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   Colt's tooth, an imperfect or superfluous tooth in young
      horses.

   To cast one's colt's tooth, to cease from youthful
      wantonness. "Your colt's tooth is not cast yet." --Shak.

   To have a colt's tooth, to be wanton. --Chaucer.
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The Collaborative International Dictionary of English v.0.48:

Colt \Colt\ (k[=o]lt; 110), v. i.
   To frisk or frolic like a colt; to act licentiously or
   wantonly. [Obs.]
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         They shook off their bridles and began to colt.
                                                  --Spenser.
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The Collaborative International Dictionary of English v.0.48:

Colt \Colt\, v. t.
   1. To horse; to get with young. --Shak.
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   2. To befool. [Obs.] --Shak.
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WordNet (r) 3.0 (2006):

colt
    n 1: a young male horse under the age of four
    2: a kind of revolver