A sack
Encroachment is when a defensive player makes contact with an offensive player at the line of scrimmage prior to the ball being snapped. Unabated to the quarterback is when a defensive player charges across the line and is on his way to the quarterback before the ball is snapped.
The quarterback is reading the defense and communicating with the offensive line. He might be pointing out a possible blitz or calling out a blocking assignment.
nickleback
When one or more of the linebackers (and occasionally defensive backs) directly attacks the offensive backfield (where the quarterback and halfback are). The intent of a run blitz is to prevent the offense from effectively running the ball. The run blitz can be countered with a pass, as less defenders are prepared for a pass.
Jay Cutler was the starting quarterback in Denver before Kyle Orton.
Paul Thompson was the quarterback of the Oklahoma Sooners before Sam Bradford.
If an offensive lineman moves, a false start penalty will be called. It is not fair to the defense if the lineman moves before the snap because it would give the offense a huge advantage.
The "pocket" is a horseshoe shaped area formed by offensive linemen that drop back and protect the quarterback during a pass play. In theory, if the quarterback remains within the pocket, he will have sufficient time to find a receiver and throw a pass. If defensive players penetrate the pocket before the pass is thrown, the quarterback is either sacked or forced to run out of the pocket...and then he's on his own.
Seven, of which two are eligible receivers. All other offensive players must be at least one yard behind the line of scrimmage (the exception being the quarterback) for one second before the ball is snapped.
Vinny Testaverde.
Dick Shiner was the Steelers' starting quarterback in 1968 and 1969.
Tommy Maddux out of UCLA