Dump, Dumped:

To lose a large quantity of your stack to another player on a particular hand or set of hands in short succession.

Duplicate:

To counterfeit, especially when the counterfeiting card matches one already present in the one's hand. In community card poker, a player or hand is said to be counterfeited when a community card does not change the value of his hand, but makes it more likely that an opponent will beat it.

Dead Hand:

A player's hand that is not entitled to participate in the deal for reasons like having been fouled by touching another player's cards, being found with the wrong number of cards, being dealt to a player who did not make the appropriate forced bets, etc.

Equity:

It is one's mathematical expected value from the current deal, calculated by multiplying the amount of money in the pot by one's probability of winning. For eg., if the pot currently contains $100, and you estimate that you have a one in four chance of winning it, then your equity in the pot in $25.

Expectation, Expected Value, EV:

As expected, it is often used in poker to mean "profitability in the long run".

Exposed Card:

If a card is faced up- exposed (while dealing etc.) deliberately or accidentally, revealed to players normally not entitled to that information during the play of the game. In some cases this card is ‘discarded’ but there are various rules on about how to handle this irregularity.