noun

• (uncountable) The study of the way sounds function in languages, including accent, intonation, phonemes, stress, and syllable structure, and which sounds are distinctive units within a language; (countable) the way sounds function within a given language; a phonological system.
  "Prospectus of a new work, entitled Pantographia: Containing accurate copies of all the known alphabets in the world. Together with an English explanation of the peculiar force of each letter: To which will be added specimens of all well-authenticated oral languages, Forming a comprehensive Digest of phonology."
• (by extension, uncountable) The study of the way components of signs function in a sign language, and which components are distinctive units within the language; (countable) the way components of signs function within a given sign language.
  "Sign language linguists have produced many volumes of description of the phonology and morphology of signs and the syntax of sign languages."