orthoepy: a term formerly used for the part of phonology that dealt with the `correct' pronunciation of words and its relation to `correct' orthography
phonology: the study of the sound system of a given language and the analysis and classification of its phonemes
oxygen: a nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gas; constitutes 21 percent of the atmosphere by volume; the most abundant element in the earth's crust