A horse. Prancer's nab.; a horse's head, used as a seal to a counterfeit pass. At the sign of the prancer's poll, i.e. the nag's head.
·noun A horse which prances. ...
Webster's Dictionary of the English Language
A bad, worn-out, foundered horse; also a cowardly or faint-hearted horse-stealer. ...
Dictionary of The Vulgar Tongue by Francis Grose
A fine horse. CANT. ...