Source : Webster's Revised Unabridged Dictionary (1913)

Sneeze \Sneeze\, v. i. [imp. & p. p. {Sneezed}; p. pr. & vb. n.
   {Sneezing}.] [OE. snesen; of uncertain origin; cf. D. snuse
   to sniff, E. neese, and AS. fne['o]san.]
   To emit air, chiefly through the nose, audibly and violently,
   by a kind of involuntary convulsive force, occasioned by
   irritation of the inner membrane of the nose.

   {Not to be sneezed at}, not to be despised or contemned; not
      to be treated lightly. [Colloq.] ``He had to do with old
      women who were not to be sneezed at.'' --Prof. Wilson.