de rigueur

from WordNet (r) 3.0 (2006)
de rigueur
    adj 1: required by etiquette or usage or fashion; "instruction
           as to when and where a silk hat is de rigueur"
from The Collaborative International Dictionary of English v.0.48
De rigueur \De ri`gueur"\ [F. See 2d {Rigor}.]
   According to strictness (of etiquette, rule, or the like);
   obligatory; strictly required.
   [Webster 1913 Suppl.]
from Moby Thesaurus II by Grady Ward, 1.0
34 Moby Thesaurus words for "de rigueur":
      accepted, acknowledged, admitted, approved, au fait, becoming,
      being done, binding, comme il faut, conformable, conventional,
      correct, customary, decent, decorous, done, formal, imperative,
      imperious, mandatory, meet, must, necessary, nice, obligatory,
      orthodox, peremptory, proper, received, recognized, required,
      right, seemly, traditional
antiflux / dictionary / de rigueur
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