faux pas /ˈfoˌpɑ, foˈ/
  失禮,失言
  faux pas  A false step; a mistake or wrong measure; especially, a slip or misstep in social etiquette; a blunder in conduct or manners that causes embarassment; as, he committed the faux pas of mentioning John's former wife.
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  faux pas
       n : a socially awkward or tactless act [syn: gaffe, solecism,
            slip, gaucherie]