The Collaborative International Dictionary of English v.0.48:

Tripod \Tri"pod\, n. [L. tripus, -odis, Gr. ?; ? (see Tri-) +
   ?, ?, foot. See Foot, and cf. Tripos, Trivet.]
   1. Any utensil or vessel, as a stool, table, altar, caldron,
      etc., supported on three feet.
      [1913 Webster]

   Note: On such, a stool, in the temple of Apollo at Delphi,
         the Pythian priestess sat while giving responses to
         those consulting the Delphic oracle.
         [1913 Webster]

   2. A three-legged frame or stand, usually jointed at top, for
      supporting a theodolite, compass, telescope, camera, or
      other instrument.
      [1913 Webster]

   Tripod of life, or Vital tripod (Physiol.), the three
      organs, the heart, lungs, and brain; -- so called because
      their united action is necessary to the maintenance of
      life.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tripod
    n 1: a three-legged rack used for support