any large prize, kitty, or accumulated stake that may be won in gambling, such as a pool in poker that accumulates until the betting is opened with a pair of jacks or higher
2.
hit the jackpot
a. to win a jackpot
b. informal to achieve great success, esp through luck
"big prize," 1944, from obsolete poker sense (1881) of progressive antes that begin when no player has a pair of jacks or better. Earlier, in criminal slang, it meant "trouble," especially "an arrest" (1902).