The Collaborative International Dictionary of English v.0.48:

Curvet \Cur"vet\ (k[^u]r"v?t or k[^u]r-v?t"; 277), n. [OE.
   corvet, It.corvetta: cf. F. courbette. See Curve, and cf.
   Corvetto.]
   1. (Man.) A particular leap of a horse, when he raises both
      his fore legs at once, equally advanced, and, as his fore
      legs are falling, raises his hind legs, so that all his
      legs are in the air at once.
      [1913 Webster]

   2. A prank; a frolic.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Curvet \Cur"vet\, v. i. [imp. & p. p. Curveted or -vetted;
   p. pr. & vb. n. Curveting or -vetting.] [Cf. It.
   corvettare. See Curvet, n.]
   1. To make a curvet; to leap; to bound. "Oft and high he did
      curvet." --Drayton.
      [1913 Webster]

   2. To leap and frisk; to frolic. --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Curvet \Cur"vet\, v. t.
   To cause to curvet. --Landor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

curvet
    n 1: a light leap by a horse in which both hind legs leave the
         ground before the forelegs come down [syn: curvet,
         vaulting]
    v 1: perform a leap where both hind legs come off the ground, of
         a horse