—n. 1. a small or narrow opening, as in a wall, for looking through, for admitting light and air, or, particularly in a fortification, for the discharge of missiles against an enemy outside. See illus. under battlement. 2. an opening or aperture.
3. a means of escape or evasion; a means or opportunity of evading a rule, law, etc.: There are a number of loopholes in the tax laws whereby corporations can save money.