Mycenaean inscriptions show that the three labiovelars kʷ, gʷ, and gʷʰ inherited from Proto-Indo-European were still distinct from other velars and from labials in most environments during the second millennium BCE. They were represented with the letter qoppa, written Ϙ. A notable exception was when adjacent to [u]; in such instances, the labiovelar unrounded, as it also did before [j]. Both of these developments took place in Proto-Greek (Proto-Greek and Common Greek) (Stephens …