a final contest, confrontation, or test that will decide the outcome of something or settle a dispute;
e.g. There was a showdown during which everyone was yelling and many hurtful things were said.
(noun)
the rule that each remaining player must show the cards they hold at the end of a round of poker in order to determine whose are strongest and thus who wins;
e.g. He was eager for the showdown, since he was certain that he had a winning hand of cards.