loophole

A way of avoiding or escaping a cost or legal burden that would otherwise apply by means of an omission or ambiguity in the wording of a contract or law.

A small hole or slit in a wall, especially one through which small arms may be fired.

A small aperture, narrow toward the outside and splayed within, in the walls of a fortification or of any similar structure, through which small-arms may be fired at an enemy, or observations may be taken.

An opening into or out of anything; a hole or aperture that gives a passage or the means of escape: often used figuratively, and especially of an underhand or unfair method of escape or evasion.

A small opening, as in the walls of fortification, or in the bulkhead of a ship, through which small arms or other weapons may be discharged at an enemy.

A hole or aperture that gives a passage, or the means of escape or evasion.

An amibiguity or unintended omission in a law, rule, regulation, or contract which allows a party to circumvent the intent of the text and avoid its obligations under certain circumstances. — used usually in a negative sense; — distinguished from escape clause in that the latter usually is included to deliberately allow evasion of obligation under certain specified and foreseen circumstances.

A method of escape, especially an ambiguity or exception in a rule that can be exploited in order to avoid its effect.

A slit in a castle wall. Later: any similar window for shooting a weapon or letting in light.

To prepare a building for defense by preparing slits or holes through which to fire on attackers