Source : Webster's Revised Unabridged Dictionary (1913)

Cogwheel \Cog"wheel`\, n.
   A wheel with cogs or teeth; a gear wheel. See Illust. of
   {Gearing}.

Source : WordNet®

cogwheel
     n : a toothed wheel that engages another toothed mechanism in
         order to change the speed or direction of transmitted
         motion [syn: {gear}, {gear wheel}]