Dead card
A dead card is a card which a player that drew it is either incapable of playing, or which has simply become irrelevant. This may also be expressed with the phrase dead draw if the card was just drawn from the deck.
For example, drawing basic land cards late in the game are dead draws, as they do not have any advantageous effect on their own, and no other cards are available for which additional mana is necessary. A card may also be dead because it is incapable of stopping an opponent's advances, such as drawing Doom Blade against an opponent who plays a mono-black deck, or who plays no creatures.
Several kinds of abilities help avoid the problems of dead cards. Looting and rummaging effects can replace dead cards with useful ones in the hand. Some abilities or spells which use discarding as a cost are very efficient if dead cards are available for them to "consume". Some of these include graveyard recursion or cloning, effectively exchanging the dead card for one from the graveyard or a copy of something useful. Cards with cycling prevent themselves from being dead cards by making it easy to replace them. Scry helps draw "live" cards sooner rather than later, while Surveil and similar abilities help avoid drawing dead cards at all.