The Collaborative International Dictionary of English v.0.48:

Vulgarism \Vul"gar*ism\, n. [Cf. F. vulgarisme.]
   [1913 Webster]
   1. Grossness; rudeness; vulgarity.
      [1913 Webster]

   2. A vulgar phrase or expression.
      [1913 Webster]

            A fastidious taste will find offense in the
            occasional vulgarisms, or what we now call "slang,"
            which not a few of our writers seem to have
            affected.                             --Coleridge.
      [1913 Webster]

WordNet (r) 3.0 (2006):

vulgarism
    n 1: an offensive or indecent word or phrase [syn: obscenity,
         smut, vulgarism, filth, dirty word]
    2: the quality of lacking taste and refinement [syn:
       coarseness, commonness, grossness, vulgarity,
       vulgarism, raunch]