In football, a split end is a term used to describe a type of receiver that is positioned on the line of scrimmage and is furthest away from the center. The split end generally lines up on the opposite side of the tight end and has a significant gap between the rest of the offensive line. The distance or "split" from the rest of the offense is where the name split end is drawn from. This position is used the meet the requirement that says there needs to be at least 7 players on the line of scrimmage before the snap.
As wide receivers, split ends tend to receive the most passes and are typically the quickest, most athletic, and alert players on the field. Split ends are used to run passing routes and spread the area that the defenses need to cover to open up the center of the field for runs. The position is commonly abbreviated as SE or X receiver.