Plain English Meaning
A planned turn-around maneuver shown on an approach chart that lets you swing the aircraft around so you end up heading the right way for the approach.
Full Definition
A charted instrument procedure maneuver used to reverse the direction of flight in order to align the aircraft inbound on a final approach course or other published track. Common forms include the procedure turn, the holding pattern in lieu of a procedure turn, and the teardrop. It is depicted in both plan view and profile view on instrument approach charts and must be flown within the published distance and altitude limits.