In hockey, the slot is a rectangular area that extends toward the blue line. It is also the fourth position in a flying display. The word slot is derived from the verb sleutana, which is cognate with the German Schloss. The word has been used in English since at least the 15th century.
They’re positioned slightly off the line of scrimmage
Slot receivers are smaller, quicker and nimbler than wide receivers. They work off the line of scrimmage on quick routes and try to create mismatches against linebackers. They typically do not have the same size and strength as a wide receiver, and are not as effective at throwing the ball down the field.
Slot receivers usually line up behind the line of scrimmage and are a key part of multiple-ball receiver formations. The slot is filled by a wide receiver, a tight end, or a running back.