Definition - The study of phonemes, i.e. meaningful speech sounds. As opposed to phonetics, which is the study of phones, i.e, speech sounds.

Etymology -
The word was coined by combining the Greek phone, sound or voice, with ology, the study of.

Oxford English Dictionary -
Its first citation is from 1799:
"Specimens of all well authenticated oral languages; forming a comprehensive digest of phonology."
(E. Fry Pantographia (title-p.))

Please comment