AUDIBLE—A call made in code by the quarterback at the line of scrimmage to change or "check off" the play called in the huddle.
BLOCKING DOWN—A tactic that calls for a lineman to block the first opponent lined up to his "inside" in a direction away from the flow of the play.
CHOP BLOCK—A double-team tactic in which one offensive lineman "straightens up" a defensive player with a block before a back chops the defender across the legs. Pete Rozelle has urged NFL coaches not to teach the chop block because it can lead to knee injuries. But it has not been ruled illegal.
FINESSE OR INFLUENCE BLOCK—A guileful tactic to move one or more defenders in the wrong direction by some means other than physical force. For example, a right guard will pull to his left, thus occupying the attention of a linebacker, and then the play will go to the right.
FULL-HOUSE BACKFIELD—An alignment which positions three running backs, none of them flanked wide, behind the quarterback. In essence, the old T formation.
GAP—The space between two offensive linemen on the line of scrimmage.
LEAD BLOCK—One made by a running back hitting the hole ahead of the ballcarrier.
POCKET—A protective area in the backfield that the blockers establish and in which the quarterback stands while executing passing plays. A "moving pocket" insulates the quarterback as he rolls right or left.
PULL—An action taken by one or both guards, or occasionally a tackle, to provide extra blocking on a wide run or to sucker a defender out of the play. The pulling lineman vacates his customary spot in the line, runs behind and parallel to the line of scrimmage and then turns upheld to lead the ballcarrier, blocking when needed.