Keyhole

a hole for inserting a key in a lock, esp. one in the shape of a circle with a rectangle having a width smaller than the diameter of the circle projecting from the bottom.

Also called key. Basketball . 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, esp. with reference to information gained as if by peeping through a keyhole.

snooping and intrusive

a keyhole investigator.