A dead card is a card that is no longer available to help you. In seven card stud, for example, a pair of kings in the hole is less strong if the two remaining kings are two other players' door cards, and therefore dead.
Dead money is money that was put in a pot by a player who has since folded.
Deal To deal is to give out the cards during a hand. The person who does this is called the dealer. At most private games, players take turns dealing. To be dealt in is to be given cards during a hand. To be dealt out or dealt around is not to be given cards.