Beyond the pale
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The phrase beyond the pale dates back to the 14th century, when the part of Ireland that was under English rule was delineated by a [boundary] made of such [stakes] or fences, and known as the English Pale. To travel outside of that boundary, beyond the pale, was to leave behind all the rules and institutions of English society, which the English modestly considered synonymous with [civilization] itself.
Beyond the pale meaning & definition 1 of Beyond the pale.
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If someones behaviour is beyond the pale, it is unacceptable:
Beyond the pale meaning & definition 2 of Beyond the pale.