Check

From Ultipedia

On offense the check is the individual marking you. On defense the check is the individual you are marking.

The check is also the action that restarts gameplay after any stoppage. The throw offers the disc to the marker, who checks the disc in by touching it. The thrower may not attempt a pass before the check has occured. If no defender is close enough to touch the disc, the offense may perform an offensive self-check. If there is a stoppage of play while the disc is on the ground (ie after an injury call while the disc is in the air), the defender closest to the disc may put it in to play using a defensive self check.