Source : Webster's Revised Unabridged Dictionary (1913)

Fulcrum \Ful"crum\, n.; pl. L. {Fulcra}, E. {Fulcrums}. [L.,
   bedpost, fr. fulcire to prop.]
   1. A prop or support.

   2. (Mech.) That by which a lever is sustained, or about which
      it turns in lifting or moving a body.

   3. (Bot.) An accessory organ such as a tendril, stipule,
      spine, and the like. [R.] --Gray.

   4. (Zo["o]l.)
      (a) The horny inferior surface of the lingua of certain
          insects.
      (b) One of the small, spiniform scales found on the front
          edge of the dorsal and caudal fins of many ganoid
          fishes.

   5. (Anat.) The connective tissue supporting the framework of
      the retina of the eye.

Source : WordNet®

fulcrum
     n : the pivot about which a lever turns
     [also: {fulcra} (pl)]