loophole

n. 1. (Mil.) 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. [ 1913 Webster ]

2. A hole or aperture that gives a passage, or the means of escape or evasion. [ 1913 Webster ]

3. 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; as, a loophole in the law big enough to drive a truck through. [ PJC ]