Glossary C:

C

Carry
or carries is a statistic referring to the number of times a rushing player attempts to advance the ball. A ballcarrier can be any player that attempts to advance the ball during an offensive play, regardless of position.
center (C)
a player position on offense. The center usually snaps the ball. The middle lineman is not always the snapper.
center-eligible
a trick play (made famous by the film M*A*S*H[citation needed]) wherein at the snap, the entire offensive line is to one side of the center so that he is on the end and therefore is an eligible receiver.
centre
Canadian "center"
chain
the 10-yard long chain that is used by the chain crew (aka "chain gang") to measure for a new series of downs.
chuck and duck
A degrading way to refer to the Run And Shoot offensive strategy.
checkdown
The checkdown pass is when the quarterback has to complete a short pass to a running back or tight end as a last resort to avoid a sack. Handling a checkdown situation is for a running back to catch these short pass, then use his speed, agility and power to run for extra yardage.
clipping
an illegal block in which the victim is blocked from the back and at or below the waist; the penalty is 15 yards. Originally, clipping was defined as any block from the back, but is now restricted to blocks at or below the waist. Other blocks from the back are now punished with 10-yard penalties.
coffin corner
the corner of the field of play. A punter, if he is close enough, will often attempt to kick the ball out of bounds close to the receiving team's goal line and pin them back near their own end zone.
comeback route
a receiver or tight end route where the player runs straight upfield a specified number of yards (could be a short or medium route), plants hard, and turns and runs back towards the sideline at a 45 degree angle. Often confusingly named, a wide receiver doesn't come back towards the quarterback, instead he tries to catch the ball and guarantee getting out of bounds.
completion percentage
the percentage of passes thrown by a player that are completed. For example, if a running back throws one pass all season and completes it his completion percentage would be 100%.
contain
a defensive assignment. On outside runs such as the sweep, one defensive player (usually a cornerback or outside linebacker) is assigned to keep the rusher from getting to the edge of the play and turning upfield. If executed properly, the rusher will have to turn upfield before the play calls for it, giving the linebackers a better chance of stopping the play for little or no gain.
cornerback (CB)
a defensive back who lines up near the line of scrimmage across from a wide receiver. Their primary job is to disrupt passing routes and to defend against short and medium passes in the passing game, and to contain the rusher on rushing plays.
Cover
There are two general schemes for defending against the pass:

1. Man-to-man, where each eligible receiver is covered by a defensive back or a linebacker.
2. Zone, where certain players (usually defensive backs and/or linebackers, though occasionally linemen as well) are assigned an area on the field (Flat, Hook, Curl and Deep) that they are to cover.

Common types of coverage:

1. Cover Zero - Strict man-to-man coverage with no help from safeties (usually a blitz play with at least five men crossing the line of scrimmage)
2. Cover One - Man-to-man coverage with at least one safety not assigned a player to cover who can help out on deep pass routes.
3. Cover Two - Zone coverage with the safeties playing deep and covering half the field each. Can be Cover 2 man, where every receiver is covered by a defensive player, or Cover 2 Zone (Also know as Tampa 2), where CB covers Flat zone, OLB Hook Zone and MLB Curl Zone.
4. Cover Three - Zone coverage as above, but with extra help from Strong Safety/Cornerback, so that each player covers one-third of a deep zone.
5. Cover Four - As above, with the corners and safeties dropping into deep coverage, with each taking one-fourth of the width of the field. Also referred to as Quarters.

counter
a running play in which the running back will take a step in the apparent direction of the play (ie, the direction the line is moving), only to get the handoff in the other direction. Weak side linemen will sometimes pull and lead the back downfield (sometimes called a counter trap), but not necessarily. The play is designed to get the defense to flow away from the action for a few steps as they follow the linemen, allowing more room for the running back.
crackback block
an illegal block delivered below the opponent's waist by an offensive player who had left the area of close line play and then returned to it, or was not within it at the snap. The term is also used to describe a legal block (delivered from the front, or from the side with the offensive player's helmet in front of the blocked player) by a wide receiver on a player who lined up inside of him.
cut

1. a sharp change of direction by a running player. Also called a cutback.

cut blocking
a blocking technique in which offensive linemen, and sometimes other blockers, block legally below the waist (i.e., from the front of the defensive player) in an attempt to bring the defenders to ground, making them unable to pursue a running back for the short time needed for the back to find a gap in the defense. The technique is somewhat controversial, as it carries a risk of serious leg injuries to the blocked defenders.

The San Francisco 49ers of the 1980s and early 90's were noted for their cut-blocking (and leg-whipping, which is illegal), a tactic that was later adopted in mid-90's by the NFL's Denver Broncos. The Broncos gained a degree of notoriety for their cut-blocking techniques (often called "dirty" play by their opponents) which produced the NFL's best rushing attack for a decade, but also resulted in several defensive players opponents of the Broncos being injured by cut blocks. In a Monday Night Football game in 2004, defensive lineman Anthony Williams of the Cincinnati Bengals was lost to the season on a block (by the Broncos tackle George Foster), and in 2005, Jacksonville Jaguars defensive lineman Paul Spicer was badly injured on block by Broncos tackle Matt Lepsis. Responding to the criticism, in 2004 Broncos coach Mike Shanahan showed local reporters some NFL game film (only seen and used by coaches) that demonstrated how nearly every team in the NFL uses cut-blocking.

chop block
Similar to a cut block in which one offensive player blocks a defensive player below the knees and another blocks him above the waist. It is illegal to block low if a team mate is already engaged with the defensive player blocking high to prevent knee and ankle injuries.