Jackpot /(?)/

Jackpot

n.
  1. Same as jack pot. See under jack.
  2. Any larger-than-usual gambling prize formed by the accumulation of unwon bets.
  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.
  4. An unusually large success in an enterprise, either unexpected or unpredictable, esp. one providing a great financial benefit.

Phrases & Compounds
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.