>Hopefully one of the Greek
>experts on the list can clarify the pronunciation of the ΓΌ
>for us.
Without Sydney Allan's Vox Graeca, I can't give all the arguments, but
generally the Attic Greek /y/ of the classical period appears to have been
front rounded, rather than central rounded. Many other dialects retained
it as a back rounded vowel.
Latin transcriptions offer one clue. The early loan words transcribe <y> as
<u> (eg cubus) but later a new letter is introduced to indicate the
non-Latin sound. This was introduced in the 1st century BC, when there were
sufficient Greek speakers in Rome.
Now Latin itself appears to have had a central rounded vowel, variously
written as <i> or <u> (eg in the alternatives optimus / optumus), so the
Greek sound must have been sufficiently different for a new letter to be
needed.
Furthermore, the sound merges in Greek with /i/ at quite an early date, so
that <y> and <i> became variant spellings, even within Latin transcriptions.
Some native Latin words then became spelled with this new letter, eg
<stylus>.
Peter