Source : Webster's Revised Unabridged Dictionary (1913)

Grinder \Grind"er\, n.
   1. One who, or that which, grinds.

   2. One of the double teeth, used to grind or masticate the
      food; a molar.

   3. (Zo["o]l.) The restless flycatcher ({Seisura inquieta}) of
      Australia; -- called also {restless thrush} and {volatile
      thrush}. It makes a noise like a scissors grinder, to
      which the name alludes.

Source : WordNet®

grinder
     n 1: a large sandwich made of a long crusty roll split lengthwise
          and filled with meats and cheese (and tomato and onion
          and lettuce and condiments); different names are used in
          different sections of the United States [syn: {bomber},
          {hero}, {hero sandwich}, {hoagie}, {hoagy}, {Cuban
          sandwich}, {Italian sandwich}, {poor boy}, {sub}, {submarine},
           {submarine sandwich}, {torpedo}, {wedge}, {zep}]
     2: grinding tooth with a broad crown; located behind the
        premolars [syn: {molar}]
     3: machine that processes materials by grinding or crushing
        [syn: {mill}]
     4: a machine tool that polishes metal