A defensive player in football that is responsible for outside containment and is involved in the following depending on the defensive play call and what the defense is doing: blitzing the quarterback, tackling the running back, covering the tight end and moving into pass coverage. In most formations, there are two outside linebackers, the strongside linebacker (known as the left outside linebacker) and the weakside linebacker (known as the right outside linebacker).
Also referred to as "Buck."
The strongside linebacker will lineup across from the tight end or the side with the most offensvie personnel and will often be resposible for stuffing and tackling the running back (who is usually following a block from the tight end or fullback) during running plays and either be covering the tight end in passing plays or blitzing the quarterback. The weakside linebacker is usually found in passing coverage. Both are part of the linebacking core which generally lineup 3-5 yards from the line of scrimmage