ὗ

• ὖ (û) (standard, with smooth breathing)

• Pronounced as /hy:/ in Koine Greek, reflecting the rare use of rough breathing.

From the long version of the vowel sound it was used to represent, like the names of other vowel letters, preceded by the rough breathing (aspiration) /h/, which was found at the start of all ordinary Ancient Greek words that started with this letter.

ὗ • (hû) n (indeclinable)

1. (Koine) alternative form of ὖ (û), upsilon (the name of the letter υ)
   • Myrinus, Greek Anthology 11.67.1:^[1]

     Ὗ τετρηκόσι᾿ ἐστίν· ἔχεις δὲ σὺ τοὺς ἐνιαυτοὺς
     δὶς τόσσους, τρυφερὴ Λαῒ κορωνεκάβη,
     Σισύφου ὦ μάμμη, καὶ Δευκαλίωνος ἀδελφή.
     βάπτε δὲ τὰς λευκάς, καὶ λέγε πᾶσι τατᾶ.

     Hû tetrēkósi’ estín; ékheis dè sù toùs eniautoùs
     dìs tóssous, trupherḕ Laï̀ korōnekábē,
     Sisúphou ô mámmē, kaì Deukalíōnos adelphḗ.
     bápte dè tàs leukás, kaì lége pâsi tatâ.

     • 1918 translation by W. R. Paton

       The letter υ signifies four hundred, but your years are twice as much, my tender Lais, as old as a crow and Hecuba put together, grandmother of Sisyphus and sister of Deucalion. But dye your white hair and say “tata” to everyone.

   • 6th century AD, Stephanus of Byzantium, Greek Anthology 9.385.20:^[2]

     ὗ, μακάρων ἔρις ὦρτο, φέρει δ᾽ ἐπὶ κάρτος Ἀχαιοῖς.

     hû, makárōn éris ôrto, phérei d’ epì kártos Akhaioîs.

     (please add an English translation of this quotation)

The Ancient Greek name of the letter upsilon is usually written ὖ (û), with a smooth breathing, but ὗ (hû), with a rough breathing, appears as a less common alternative form of the letter-name. Evidence for the aspirated pronunciation also exists in the form of the traditional name ϩⲉ ("He") of the corresponding Coptic letter Ⲩ, and a spelling הוה found in a Hebrew-script fragment listing the names of Greek letters.^[3]

• ῡ̔οειδής (hūoeidḗs)

• Appendix:Greek alphabet
• ὖ ψιλόν

• “Υυ”, in Liddell & Scott (1940) A Greek–English Lexicon, Oxford: Clarendon Press
• M. Triantafyllidis, Dictionary of Standard Modern Greek – In ancient Greek pronunciation, υ was pronounced with rough breathing, though this was later dropped in most forms.