GENERAL PRINCIPLES, ANASTROPHE,
CHANGE OF ACCENT IN DECLENSION,
INFLECTION AND COMPOSITION,
The penult, if accented and long, takes
the circumflex when the ultima is short by nature (νῆσος, ταῦτα).
In all other cases it has the acute (φόβος, λελυκότος, τούτου).
Apparent exceptions are ὥστε,
οὔτις, ἥδε (properly ἧδε).
A final syllable containing a vowel short
by nature followed by ξ or ψ does not permit the acute to stand
on the antepenult (οἰκοφύλαξ); but the circumflex may stand on the
The ultima, if accented and short, has
the acute (ποταμός); if accented and long, has either the acute
(λελυκώς), or the circumflex (Περικλῆς).
When the ultima is long, the acute cannot
stand on the antepenult, nor the circumflex on the penult. Thus,
ἄνθρωπου and δῶρου are impossible.
When the ultima is short, a word, if
on the ultima, has the acute:
on a short penult, has the acute:
on a long penult, has the circumflex:
on the antepenult, has the acute:
When the ultima is long, a word, if
on the ultima, has the acute or the
circumflex: ἐγώ, σοφῶς.
on the penult, has the acute:
Cf. Greek pronunciation (Elpenor's Lesson 1)
Select On-Line Greek Resources
Reference address : https://www.ellopos.net/elpenor/lessons/greek-accentuation.asp?pg=4