What is "nasal index"

Nasal \Na"sal\ (n[=a]"zal), a. [F., from L. nasus the nose. See Nose.]

1. (Anat.) Of or pertaining to the nose.

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.

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

   Nasal index (Anat.), in the skull, the ratio of the transverse the base of the aperture to the nasion, which latter distance is taken as the standard, equal to 100.