KEYHOLE

The hole in a lock where the key is inserted and turns.

Any small opening resembling the hole for a key in shape or function.

A circle cut out of a garment as a decorative effect, typically at the front or back neckline of a dress.

(ordnance) To strike a target after wobbling in flight so that the long axis of the bullet does not follow the line of flight; typically due to insufficient spin resulting from the rifling in the barrel.