/ ˈluːphəʊl; NAmE -hoʊl/ noun
loophole (in sth) a mistake in the way a law, contract, etc. has been written which enables people to legally avoid doing sth that the law, contract, etc. had intended them to do :
a legal loophole
to close existing loopholes
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WORD ORIGIN
late 16th cent. (denoting an arrow slit): from obsolete loop embrasure + hole .