Emily Dickinson Lexicon

JOCK'EY, n. [said to be from Jackey, a diminution of Jack, John; primarily, a boy that rides horses.]

1. A man that rides horses in a race. – Addison.
2. A dealer in horses; one who makes it his business to buy and sell horses for gain. Hence,
3. A cheat; one who deceives or takes undue advantage in trade.