faux pas

from WordNet (r) 3.0 (2006)

faux pas
    n 1: a socially awkward or tactless act [syn: {faux pas},
         {gaffe}, {solecism}, {slip}, {gaucherie}]

from The Collaborative International Dictionary of English v.0.48

faux pas \faux` pas"\ (f[=o]` p[.a]"). [F. See {False}, and
   {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.
   [1913 Webster +PJC]

from Moby Thesaurus II by Grady Ward, 1.0

20 Moby Thesaurus words for "faux pas":
      blooper, blunder, boner, boo-boo, botch, break, bungle, gaffe,
      howler, impropriety, indecorum, indiscretion, misjudgment, misstep,
      oversight, pratfall, screamer, solecism, stumble, stupidity

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