The Collaborative International Dictionary of English v.0.48:

Caper \Ca"per\, v. i. [imp. & p. p. Capered p. pr. & vb. n.
   capering.] [From older capreoll to caper, cf. F. se cabrer
   to prance; all ultimately fr. L. caper, capra, goat. See
   Capriole.]
   To leap or jump about in a sprightly manner; to cut capers;
   to skip; to spring; to prance; to dance.
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         He capers, he dances, he has eyes of youth. --Shak.
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