Source : Webster's Revised Unabridged Dictionary (1913)

Sneer \Sneer\, v. i. [imp. & p. p. {Sneered}; p. pr. & vb. n.
   {Sneering}.] [OE. sneren, Dan. sn?rre to snarl or grin (like
   a dog); cf. Prov. E. sneer to grin, sner to snort, snert to
   sneer at. See {Snore}, v. i.]
   1. To show contempt by turning up the nose, or by a
      particular facial expression.

   2. To inssinuate contempt by a covert expression; to speak
      derisively.

            I could be content to be a little sneared at.
                                                  --Pope.

   3. To show mirth awkwardly. [R.] --Tatler.

   Syn: To scoff; gibe; jeer.

   Usage: {Sneer}, {Scoff}, {Jeer}. The verb to sneer implies to
          cast contempt indirectly or by covert expressions. To
          jeer is stronger, and denotes the use of several
          sarcastic reflections. To scoff is stronger still,
          implying the use of insolent mockery and derision.

                And sneers as learnedly as they, Like females
                o'er their morning tea.           --Swift.

                Midas, exposed to all their jeers, Had lost his
                art, and kept his ears.           --Swift.

                The fop, with learning at defiance, Scoffs at
                the pedant and science.           --Gay.

Source : WordNet®

sneering
     adj : expressive of contempt; "curled his lip in a supercilious
           smile"; "spoke in a sneering jeering manner"; "makes
           many a sharp comparison but never a mean or snide one"
           [syn: {supercilious}, {snide}]