'Jackpot' definitions:

Definition of 'jackpot'

noun

The cumulative amount involved in a game (such as poker) [syn: pot, jackpot, kitty]

noun

Any outstanding award

From: GCIDE

Jackpot \Jackpot\, n.
1. Same as jack pot. See under jack. [PJC]
2. Any larger-than-usual gambling prize formed by the accumulation of unwon bets. [PJC]
3. The highest gambling prize awarded in a gambling game in which smaller prizes are also awarded, especially such a prize on a slot machine. [PJC]
4. An unusually large success in an enterprise, either unexpected or unpredictable, esp. one providing a great financial benefit. [PJC]
hit the jackpot to receive an unexpectedly large (or the largest possible) benefit from an enterprise; as, after prospecting for years, he finally hit the jackpot when he discovered a silver lode. [PJC]