Source : Webster's Revised Unabridged Dictionary (1913)

Odontoid \O*don"toid\, a. [Gr. ?; 'odoy`s, 'odo`ntos, a tooth +
   ? form: cf.F. odonto["i]de.] (Anat.)
   (a) Having the form of a tooth; toothlike.
   (b) Of or pertaining to the odontoid bone or to the odontoid
       process.

   {Odontoid bone} (Anat.), a separate bone, in many reptiles,
      corresponding to the odontoid process.

   {Odontoid process}, or {Odontoid peg} (Anat.), the anterior
      process of the centrum of the second vertebra, or axis, in
      birds and mammals. See {Axis}.

Source : WordNet®

odontoid process
     n : a toothlike process at the back of 2nd vertebra of the neck