|Definition - The part of grammar that deals with pronunciation; especially, correct pronunciation. In the latter sense, the opposite of orthoepy is barbarism.|
Etymology - The term derives from the Greek orthos, straight + poieo, make.
Oxford English Dictionary - Its first citation is from 1773:
"A new Dictionary of the English Language: containing not only the explanation of words … but likewise their orthoepia or pronunciation in speech."
(W. Kenrick (title))