Source : Webster's Revised Unabridged Dictionary (1913)

Notochord \No"to*chord\, n. [Gr. ? the back + E. chord.] (Anat.)
   An elastic cartilagelike rod which is developed beneath the
   medullary groove in the vertebrate embryo, and constitutes
   the primitive axial skeleton around which the centra of the
   vertebr[ae] and the posterior part of the base of the skull
   are developed; the chorda dorsalis. See Illust. of
   {Ectoderm}.

Source : WordNet®

notochord
     n : a flexible rodlike structure that forms the supporting axis
         of the body in the lowest chordates and lowest
         vertebrates and in embryos of higher vertebrates