- a hole for inserting a key in a lock, especially one in the shape of a circle with a rectangle having a width smaller than the diameter of the circle projecting from the bottom.
- the area at each end of the court that is bounded by two lines extending from the end line parallel to and equidistant from the sidelines and terminating in a circle around the foul line.
- extremely private or intimate, especially with reference to information gained as if by peeping through a keyhole.
- snooping and intrusive: a keyhole investigator.
- an aperture in a door or a lock case through which a key may be passed to engage the lock mechanism
- any small aperture resembling a keyhole in shape or function
- a transient column of vapour or plasma formed during the welding or cutting of materials, using high energy beams, such as lasers
