Sack – Tackling the “Quarterback” before he releases the ball while he’s still behind the “Line of Scrimmage”

Safety – either: 1) the defender who lines up farthest from the offense as the last line of defense before the goal line, or 2) tackling a “Ball Carrier” in his own “End Zone”; worth two points

Safety Blitz – a defensive play in which one or both of the safeties “Rush” the “Quarterback”

Safety Valve – a short quick pass to a “Running Back” the “Quarterback” makes when no “Receivers” are “Open” farther downfield and the defenders are closing in

Salary Cap – the largest amount of money a team can pay its players in a single season

Scheme – the strategy employed by the offense or defense and the formations they use

Scramble – the “Quarterback” runs behind the “Line of Scrimmage” to evade defenders until the “Receivers” can get open

Scrambler – a “Quarterback” skilled at “Scrambling”

Screen Pass – a short pass to a “Running Back”; the blocking plan for a screen pass is different because the offensive linemen generally let the defensive linemen through in the interest of moving to protect the running back’s outside route 

Scrimmage – a practice game early in the preseason

Secondary – the defensive backs behind the linebacker and are primarily concerned with defending against the pass, or the area of the field these backs are responsible for defending 

Second Forward Pass – a player catches a “Forward Pass” behind the “Line of Scrimmage” and then throws another “Forward Pass”; this is an illegal maneuver resulting in a five yard penalty

Series – a team’s four downs to get 10 yards; a new series begins with every “First Down”
Shift – one or more players to a different position in the formation before the ball is snapped to confuse the opposition

Shotgun – an offensive formation in which the “Quarterback” lines up five to seven yards behind the center to allow the “Quarterback” time to scan the defensive formation

Side Judge – the official lines up 20 yards behind the defensive “Line of Scrimmage” and serves many of the same purposes as “Back Judge”

Sidelines – the border of the field of play marking the out of bounds line

Signal Caller – a player, usually the “Quarterback” who calls plays before the snap

Signals – the system of code words, numbers, or actions a team uses to disguise called plays

Single Elimination – a tournament – such as the NFL playoffs --  in which a team is eliminated after one loss

Single-Wing Formation – an uncommon formation in which three backfield players block for the ball carrier

Slant – a “Pass Pattern” in which the runner moves across the field at an angle instead of directly toward the “End Zone”

Slot – the “Gap” between a “Tackle” and the “Receiver”; the receiver lined up in this gap is called a slot receiver

Snap – when the “Center” hands or tosses the ball to the “Quarterback” or kicker to officially begin the play

Spearing – striking another player with the top of the helmet

Special Teams – the unit of players on the field during “Kickoffs” “Field Goals” “Extra Points” and “Punts”

Spike – throwing the ball toward the ground, usually in an act of celebration after a “Touchdown”

Spiral – the spinning motion a ball takes after the ball is released in a “Pass”

Split End – a “Receiver” lined up on the outside of the offensive formation

Spot – the location at which the officials place the ball before the play begins

Square In – a “Pass Pattern” in which the “Receiver” runs downfield and turns at a right angle toward the center of the field
Square Out -- a “Pass Pattern” in which the “Receiver” runs downfield and turns at a right angle toward the “Sidelines”

Squib Kick – a hard line drive kick intended to bounce on the field before it’s caught by the “Returner”; intended to minimize the “Return”

Stance – the position a player takes prior to the ball being snapped; see also “Three-Point Stance”

Stiff Arm – deflecting a tackler with by extending a straightened arm to the opponent’s chest or head, also known as a “Straight Arm”

Striking an Official – a 15 yard penalty for making hostile contact with an official, an automatic ejection from the game  

Striking an Opponent – hitting an opponent is a 15 yard penalty and can possibly lead to an ejection from the game

Strong Safety – a “Safety” who lines up in the defensive backfield even with the tight end in order to defend against the pass, but often moves closer to the “Line of Scrimmage” to help against the run

Strong Side – the side of the “Line of Scrimmage” where the “Tight End” lines up

Stunt – a deceptive maneuver by two defensive linemen in which they alter their courses toward the “Quarterback” in an attempt to confuse the linemen  

Substitution – trading out one player with another

Subway Alumni – fans of a college team who aren’t alumni of the school; the term originally applied to fans of Notre Dame who live in New York City

Succeeding Spot – where the next play will begin if no penalty is called

Suicide Squad – the group of defensive players on field during “Punts” and “Kickoffs” who fight there way through the returning team’s “Wedge”

Super Bowl – the NFL’s championship game

Sweep – an outside running play that requires two or more linemen to pull out of their normal formations to block for the ball carrier running to the outside