Dead Ball – the time after an official designates a play to be over and before another play begins
 
Defense – the team without possession of the ball, in charge of keeping the “Offense” from taking the ball into the “End Zone”

Defensive Back – the defender usually in charge of covering receivers – “Corner Backs,” “Safeties” 

Defensive Backfield – the area behind the “Defensive Line” where the “Defensive Backs” generally line up

Defensive End – a defender who lines up at the end of the “Defensive Line,” usually in charge of containment on running plays and rushing the “Quarterback” on pass plays

Defensive Holding – using the hands to hinder a receiver by holding or pushing him back from catching a pass more than five yards away from the line of scrimmage

Defensive Line – usually the largest defenders on a team, DLs line up across from the “Offensive Line”

Defensive Lineman – the players on the “Defensive Line”

Defensive Tackle – a defender who lines up on the interior of the “Defensive Line”

Defensive Team – See “Defense”

Delay of Game – allowing the “Play Clock” to drop to zero before calling a play and snapping the ball, having more players than allowed on the field, or calling a “Time-Out” when none remain; results in a 5 yard penalty

Dime Back – a sixth “Defensive Back” brought in for “Dime Coverage”

Dime Coverage – a defensive strategy employing six “Defensive Backs,” as opposed to the usual four, generally only used in long passing situations 

Dime Package – See “Dime Coverage”

Division – a conference sub division; the NFL has four divisions per “Conference”

Double Coverage – two defenders covering the same receiver, usually only utilized for the best receivers, as this takes a “Defensive Back” away from his usual coverage responsibilities

Double Foul – when both teams commit a penalized offense during the same play, usually negates the need for penalty enforcement

Double Team – See “Double Coverage”

Down – an entire play from the time the ball is snapped until the officials rule it a “Dead Ball;” the offense gets four downs to move the ball 10 yards at a time

Down and In – A “Pass Pattern” in which the receiver runs down field and “Cuts” toward the center of the field

Down and Out -- A “Pass Pattern” in which the receiver runs down field and “Cuts” out toward the sidelines

Down Box – A sign carried by an assistant official keeping count of the “Down”

Down Lineman – a “Defensive Lineman”

Draft – The NFL Draft, alternatively called the Player Selection Meeting, is an annual April event, in which the National Football League teams select new players for their rosters. The majority of the players come from college football. Fans can receive free tickets to attend the event on a first-come, first-served basis. In order to accommodate crowds, the Draft has moved several times to larger venues. The order in which teams get to pick players is determined by a set of rules that aim to provide a fair chance to each franchise. Expansion teams, if any, are given the first pick and the previous year’s Superbowl champions are the last to pick (the runner up team chooses second to last.) The draft takes place in timed rounds, during which team representatives must make their choices. Teams may also enter into negotiations with each other before, during or after the draft to trade players.

Draft Choice – A draft choice is a player who has been picked to play for an NFL (National Football League) team during their annual Player Selection Meeting. This meeting is more commonly referred to as the NFL draft. In order to be eligible to participate in the draft, a player must have been out of high school for a minimum of three years. The majority of drafted players come from college football, although there are some independent players and others from arena or other football leagues. The draft order is determined by the team’s prior season, with lower ranking and expansion teams getting the first picks, and the Superbowl Champions picking last. There are seven timed rounds during the NFL draft, during which each team gets one draft choice. Teams may also negotiate to trade players, which can take place during or after the draft.

Draw – A draw is a deceptive football play that is designed to look like a pass, but when the quarterback drops back he hands off to a running back. In order to successfully execute this play, the running back must pretend that he is coming in to protect the runner, then accept the pass off and go in the other direction. A draw play is alternatively referred to as a delayed handoff. This type of play is usually called to counteract an overly aggressive pass rushing defense. It is called the draw play, because the goal is to attract the defensive players to the upfield, leaving more room for running the ball. The draw play is most often launched from a shotgun offense formation. When the quarterback himself runs the ball rather than handing it off, the variation is known as a quarterback draw play.

Drive – A drive is the collective term for the series of downs from the time that a team takes possession of the ball until they either score or turn possession over to the other team. It is basically, the entire series of offensive plays that a team puts together to work the ball towards the opposing team’s goal in order to score. Alternatively, ‘The Drive’ refers to a specific offensive series that took place during the 1987 AFC Championship Game between the Denver Broncos and the Cleveland Browns. This play has taken its place in football lore as one of the greatest offensive plays of all time, in which John Elway led his team on a 98 yard drive in just over 5 minutes to win the game in overtime.

Drop Back – A drop back refers to the action of a quarterback stepping backwards after receiving the snap in preparation for attempting a pass. The drop back technique is the most popular and commonly used type of football pass. The quarterback will take a certain number of steps backward as he prepares to make the pass, winding up to throw. Most players will use 3, 5 or 7 steps although some do go deeper. In order to execute a drop back pass effectively, the quarterback must have excellent balance and good control of the ball. There are numerous drills devoted to teaching this technique to players, most of which focus on balance, and on using very short quick steps, as opposed to long strides. The area that the quarterback drops into while stepping back is called the pocket. The number of steps that a player takes may vary by play.

Drop Kick – A drop kick is an extremely rare play in the NFL in which a player drops the ball and attempts to kick it through the uprights. This type of goal is worth two points. A drop kick differs from a punt. Whereas a punt is kicked from directly off of the ground, a drop kick bounces off the ground before the player kicks it. Kicking the ball after it bounces helps it to fly further. Although the drop kick was used frequently in the early days of NFL football, circa 1920-1930, there has been only one successful drop kick executed in the modern football era. It was made by Doug Flutie in 2006 and scored his team, the New England Patriots, an extra point after the touchdown made by his teammate. The rules in arena football vary slightly, and a successful drop kick extra point counts for two points, rather than one; a drop kick field goal counts for four points, instead of two.