Source : Webster's Revised Unabridged Dictionary (1913)

Phonology \Pho*nol"o*gy\, n. [Phono- + -logy.]
   The science or doctrine of the elementary sounds uttered by
   the human voice in speech, including the various
   distinctions, modifications, and combinations of tones;
   phonetics. Also, a treatise on sounds.

Source : WordNet®

phonology
     n : the study of the sound system of a given language and the
         analysis and classification of its phonemes [syn: {phonemics}]