The Collaborative International Dictionary of English v.0.48:

Nasal \Na"sal\ (n[=a]"zal), a. [F., from L. nasus the nose. See
   Nose.]
   1. (Anat.) Of or pertaining to the nose.
      [1913 Webster]

   2. (Phon.) Having a quality imparted by means of the nose;
      and specifically, made by lowering the soft palate, in
      some cases with closure of the oral passage, the voice
      thus issuing (wholly or partially) through the nose, as in
      the consonants m, n, ng (see Guide to Pronunciation,
      [sect][sect] 20, 208); characterized by resonance in the
      nasal passage; as, a nasal vowel; a nasal utterance.
      [1913 Webster]

   Nasal bones (Anat.), two bones of the skull, in front of
      the frontals.

   Nasal index (Anat.), in the skull, the ratio of the
      transverse breadth of the anterior nasal aperture to the
      height from the base of the aperture to the nasion, which
      latter distance is taken as the standard, equal to 100.
      [1913 Webster]