Face Mask – the protective bars on the front of the player’s “Helmet”; or grabbing these bars on an opponent’s helmet penalized by 5 yards if the contact is light and unintentional, and 15 yards if the facemask is used to pull the opponent’s head or force him down

Fair Catch – a player waving an arm to signal that he will not run after he catches the ball, this makes tackling the receiver illegal

Fair Catch Interference – a defender making contact with the receiver after he signals for a “Fair Catch” to hinder the reception, a 15 yard penalty 

Faking a Roughing – a rarely called 15 yard penalty against a kicker for trying to draw a “Roughing the Kicker” penalty

False Start – A 5 yard penalty against a member of the offense for movement before the ball is “Snapped”

Fantasy Football – a game in which players draft pretend teams from existing NFL players and then compete with other player’s teams; scoring is based on the player’s statistics

Fantasy League – A collective of “Fantasy Football” teams that compete against one another

Field Goal – a “Place Kicker” puts a held football through the “Uprights” for three points, generally on “Fourth Down”

Field Judge – an official – generally in charge of ruling on pass plays -- who lines up 25 yards behind the defense on the side of the “Tight End”  

Field of Play – the area marked off by the sidelines and end zones on which the game is played

Field Position – the position of the ball on the field

First and Ten – barring a penalty, this is the typical situation for the beginning of a team’s possession,; first down with 10 yards to go for another first down

First Down – the initial play in any “Series” in which a team has four plays to get 10 yards in order to earn another

Flag Football – as opposed to “Tackle Football”; a sport usually played by teams of 6 to 9 players in which a flag must be pulled from an offensive opponent’s belt instead of “Tackling” him   
Flanker – See “Receiver”

Flat – the segment of the field near the “Line of Scrimmage” between the “Sidelines” and “Hash Marks”

Flood – to direct more offensive players to a specific zone with the hope of overwhelming the defenders responsible for covering that area and forcing them to cover more than one “Receiver” 

Formation – the arrangement of the players – offensive and defensive -- on the field determined by the game situation

Forward Pass – a throw that advances the ball down field; must be thrown behind the “Line of Scrimmage”

Forward Progress – the farthest point a “Ball Carrier” reaches before he is tackled, the point where the ball is placed regardless of where the defenders might push him back to

Foul – an illegal maneuver of any sort

Franchise – an NFL team

Franchise Player – a title given a player to keep him from leaving the team as a “Free Agent,” in order to qualify for this designation, a player must be paid the average salary of the top five players in his position 

Free Agency – refers to the period of time when a player is no longer under contract and can be signed by any team

Free Agent – a player who isn’t bound by a contract to any team

Free Kick – either a punt following a “Safety” or a “Kickoff”

Free Safety – the defender who lines up deepest in the “Secondary” in the middle of the field primarily to cover the pass

Freeze – See “Controlling the Clock”

Front Four – a defensive line “Formation” of two “Ends” and two “Tackles”

Front Seven – the “Linemen” and “Linebackers”

Fullback – a “Back” who generally lines up in front of the “Half Back” and in addition to occasionally carrying the ball, he’s generally lead blocker for the “Half Back” on running plays or defends the quarterback on passing plays

Fumble – when the ball carrier loses possession of the ball during a play