The Collaborative International Dictionary of English v.0.48:

Hypoglossal \Hyp`o*glos"sal\, a. [Pref. hypo- + Gr. ? the
   tongue.] (Anat.)
   Under the tongue; -- applied esp., in the higher vertebrates,
   to the twelfth or last pair of cranial nerves, which are
   distributed to the base of the tongue. -- n. One of the
   hypoglossal nerves.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hypoglossal
    n 1: supplies intrinsic muscles of the tongue and other tongue
         muscles [syn: hypoglossal, hypoglossal nerve, nervus
         hypoglosus, twelfth cranial nerve]