Μῦς

From LSJ

γνοίης ὅσσον ὄνων κρέσσονες ἡμίονοι → you know how much better are donkeys from mules

Source

Russian (Dvoretsky)

Μῦς: Μυός ὁ Мий (брат Лида и Кара, миф. родоначальник мисийцев) Her.