In Possession: Player or team holds or controls a live ball or ball to be free-kicked.
Belongs to: Team has custody of a dead ball.
Catch: Player gains possession of a ball in flight.
Interception: Catch an opponent's pass or fumble.
Recovery: Catching a ball that is still alive after it hits the ground.
Simultaneous catch or recovery: Joint possession of a live ball by opposing inbounds players.
Blocking: Bodily contact obstructs an opponent.
Below Waist: Blocking an opponent below the waist.
Chop Block: A high-low, low-high combination block against an opponent by two players.
Block-in-the-back: Initial, above-the-waist contact against an opponent from behind.
Frame of the body: Front shoulders and below.
Blocking zone: Rectangle centered on the snapper and extending five yards laterally, and three yards longitudinally in each direction.
Clipping: Initial contact against an opponent from behind and below the waist.
Deliberate dead-ball advance: Attempt to advance the ball after any body part other than the hand or foot has touched the ground, or after the ball is declared dead.
Down: Unit of the game beginning with legal snap or free kick after ball is ready for play, ending when ball becomes dead.
Between downs: Interval of time when ball is dead.
Fair catch: A valid catch of a scrimmage kick beyond the neutral zone by team B player
Valid signal: A valid signal given by team B player by extending one hand above his head and waving his hand side to side.
Invalid signal: Signal given by team B player does not meet criteria for being valid.
Forward beyond: The direction toward opponent's end line.
Forward progress: End of advancement of ball by ball carrier or receiver of either team, as it applies to position of ball when it became dead.
Foul: Rule infraction resulting in a penalty.
Violation: Rule infraction not resulting in a penalty.
Fumble: An act of passing, kicking, or handling of ball resulting in loss of possession.
Muff: Unsuccessful attempt to recover the ball.
Batting: Willfully striking ball or changing its direction with hands or arms.
Touching: Any contact with the ball.
Blocking a scrimmage kick: Opponent of the kicking team touches the ball to try and prevent the ball from advancing beyond the neutral zone.
Sidelines: Line running end line to end line on each side of the field separating the field of play from the out of bounds area.
Goal lines: Lines at the end of the playing field extending between sidelines; part of the vertical plane that separates end zone from the playing field.
End lines: Line running between side lines ten yards between each goal line separating the end zone from the out of bounds area.
Boundary lines: Side and end lines separating in, from out of bounds.
Restraining lines: Part of the vertical plane limiting a team's alignment for free kicks.
Yard lines: Line on the playing field parallel to the end lines numbered consecutively from the goal to the 50-yard-line.
Inbounds lines: Also known as "hash marks", 24-inch lines 60 feet from the sidelines.
Nine-yard marks: 12-inch marks set 10 yards apart, and nine yards from the sidelines.
Handling the Ball
Huddle: Two or more players grouped together after the ball is made ready for play.
Hurdling: Player tries to jump with feet or knees over an opponent.
Legal: Legitimate kick of the ball with knee, lower leg, or foot by a team A player before possessing the ball.
Illegal: Non-legitimate kick of the ball.
Punt: After kicking, player drops the ball and kicks it before it hits the ground.
Drop kick: A kick made after dropping the ball on the ground.
Place kick: A kick of the ball placed on a tee or the ground by a player in possession.
Free kick: A free punt, drop kick, or place kick.
Kickoff: A free kick starting each half or following each try or field goal.
Scrimmage kick: Kick made by team A during a scrimmage before changing possession.
Return kick: A kick by team in possession during a down.
Field goal attempt: Scrimmage kick.
Scrimmage kick formation: Formation with one player at least seven yards behind the neutral zone and no player is positioned to receive a hand-to-hand snap before attempting a kick.
Loss of a down: Loss of the right to repeat a down.
The neutral zone: Space between the two lines of scrimmage extended to the side lines running the length of the ball.
Encroachment: An offensive player is either in or beyond the neutral zone after the snapper touches or simulates touching the ball before the snap.
Offside: Defensive player position assumed after the ball is made ready for play.
Passing: Throwing the ball.
Forward and backward pass: The point where the ball first strikes the ground in or behind the neutral zone beyond the point of the pass is a forward pass. All other passes are backward passes.
Crosses neutral zone: A forward pass strikes the ground or anything beyond the neutral zone inbounds.
Catchable forward pass: An untouched legal forward pass beyond the neutral zone to a player positioned to catch the ball.
Penalty: The result of committing a foul.
Scrimmage: Two teams take action during a down beginning with a snap.
Scrimmage line: The yard line and its vertical plane passing through the point of the ball nearest its own goal line extending to the sidelines.
Shift: Simultaneous change of position by at least two offensive players after the ball is ready for play.
Snapping the ball: Passing the ball with the snap of the hands backward from its position on the ground.
Series: Four consecutive downs, each beginning with a snap.
Possession series: Team continually possesses the ball in an extra period.
Enforcement: Point of enforceable violation.
Previous: Where the ball was last put in play.
Succeeding: Where the ball will be put in play.
Dead-ball: Where the ball became dead.
Spot of the foul: Where the foul occurred.
Out of bounds: Where the ball went out of bounds and became dead.
Inbounds: Intersection of the nearer inbounds line and the yard line passing through the dead ball spot, or a spot where the dead ball is left between inbounds and side line by a penalty.
Spot where run ends: Where ball is declared dead in player possession; player possession is lost on a fumble; handling of ball occurs; illegal forward or backward pass is thrown; where illegal scrimmage, or return kick is made.
Spot where kick ends: Scrimmage that crosses the neutral zone ends at the spot ball is caught or recovered or declared dead.
Basic spot: Benchmark for locating enforcement spot for penalties governed by the 3-and-1 principle.
Post-scrimmage kick spot: Spot when post-scrimmage kick enforcement applies.
Tackling: Grasping or enveloping an opponent with hands or arms.
Team and Player Designations
Teams A and B: Team A is team designated to put ball in play; team B is the opponent.
Offensive and Defensive Teams: Offensive is team with the ball, defensive is opponent.
Kicker and Holder: Kicker is any player who punts, drop kicks, or places the kicks. Holder is the player who controls the ball on the ground or tee.
Lineman and Back: Team A player on the scrimmage line when the ball is snapped; or on his scrimmage line and positioned between the end team A players also on the line of scrimmage at the snap. A lineman becomes a back before the snap when he moves to a position as a back and then stops.
Passer: Thrower of a legal forward pass.
Player: A team participant other than a replacement.
Runner and ball carrier: Player in possession of a live ball.
Snapper: Player who snaps the ball.
Substitute: A replacement for a player between downs.
Player vacancy: A team has fewer than 11 players.
Disqualified Player: Player declared ineligible for remainder of game.
Squad member: A potential player in uniform.
Tripping: Use of the leg or foot to obstruct an opponent below the knees.
Game clock: Device used to time the game.
Play clock: Visual clock used for count downs.
Forward pass: Interval between snap and completion, incompletion, or interception of the forward pass.
Free kick: Interval from when the ball is kicked until it is in possession or declared dead.
Scrimmage kick: Interval between the snap and when a scrimmage kick comes into possession or declared dead.
Running: Any play during a live ball, other than a free kick, a scrimmage kick, or forward pass play.
Field: Area of play within boundary lines.
Field of play: Area within sidelines and goal lines.
End zones: Areas at either ends of the field defined by the goal lines, side lines, and end lines.
Playing surface: Surface of the playing field.
Playing enclosure: Play area bounded by the stadium and other structures surrounding it.
Fighting: An attempt by a player, squad member, or coach to strike another in a manner not related to football.
Three-in-one principle: Applies when the penalty statement for a foul does not specify the enforcement spot.
Tackle box: Rectangular area bound by the neutral zone, lines parallel to the sidelines 5 years from the snapper, and team A's end line.