Dead Ball: A ball no longer in play.

Dead Ball Hinder: An unintentional hinder resulting in a replay of the point.

Dead Ball Serve: An illegal serve that is replayed. It does not result in a penalty to the server or the receiver, nor does it cancel any previous illegal serve.

Dead Duck Arm: A stroke mechanic disease affecting the free arm. Basically a player with this disease leaves his free arm hanging like a dead duck and this impedes a proper follow through. The free arm should rotates with the follow through to generates efficient forward momentum for a smooth/efficient stroke on both wings. Also see - Dying Limb disease.

Default: The failure of a player or team to compete in a contest because of injury, illness and so on. It results in an automatic win for the opponent.

Defective Serve: Any illegal Serve-dead ball, fault or out serve.

Defensive Players: The receiver or receiving team.

Defensive Position: The back area of the racquetball court. The position assumed to return an opponent’s shots.

Defensive Shot: A shot hit with no immediate intention to end the exchange and usually used to gain time to get back to center court, for example the ceiling shot, Z-Ball or AWB.

Diagonal Formation: A method of doubles play in which the court coverage and responsibilities are assigned by dividing the court diagonally from left front corner to the right rear corner of the court.

Diagonal Kill Shot: A risky kill attempt hit diagonally into the opposite front corner. It goes for a winner when hit properly, but when missed it comes right back to center court for a setup.

Die: When a ball loses momentum and fails to bounce high enough to be returned.

Dig: To make a good return of a difficult shot that might ordinarily have been a winner.

Dive: A maneuver extending the body into the air in order to dig for a ball.

Donut: A party you hold after a victorious match, where you shutout the oppositions, 15-0 and 15-0. See Goose Egg also.

Donut Aircraft: The aircraft that swoops down upon the crowd and drops donut confetti.

Doubles: Competition played by two teams with each having two players on a side.

Down the Wall: A shot hit parallel to and near the sidewall. Also called a wall paper shot or down the line shot.

Drill: The act of repeating an exercise again and again in order to develop a skill.

Drive Serve: A low and hard serve.

Drive Shot: a hard hit ball.

Drop Shot: A finesse shot hit with little speed and designed to barely make contact with the front wall.

Dying Limb: A stroke mechanic disease affecting the free arm. Basically a player with this disease leaves his free arm hanging like a dead duck and this impedes a proper follow through. The free arm should rotates with the follow through to generates efficient forward momentum for a smooth/efficient stroke on both wings. Also see Dead Duck Arm disease.