A running formation by a receiver where the player will begin his route in the middle of the line and then run out toward the sideline to catch the ball.
Sometimes referred to as an "out pattern."
Turn outs are one way of mixing up a passing attack by forcing different defenders to switch coverage during the play. If a receive starts his pattern in the middle a linebacker will usually provide initial coverage, but as the receiver runs out toward the sideline the linebacker either has to continue pursuit and open up his current spot for attack or allow a cornerback to take over coverage. Quarterbacks can take advantage of this confusion and delay to get the ball to the receiver as he switches from inside to outside during his running route.