Orciiomenus, a city of ancient Greece, in N. W. Bceotia, at the mouth of the Cephis-sus in Lake Copais, not far from the site of the modern village of Skripu. It was said to have been the capital of the kingdom of the Minyae, being named from Orchomenus, the son of Minyas. Homer mentions it as sending 30 ships to the Trojan war. When the Minyae were overthrown, Orchomenus joined the Boeotian confederacy. Its government was aristocratical, and after the Peloponnesian war it assisted Lysander the Spartan in his invasion of Boeotia (395 B. C), and in the following year joined Agesilaus against Thebes and Athens, and took part in the battle of Coronea. By the peace of Antalcidas (387) the Thebans acknowledged the independence of Orchomenus. They gained control of it after the battle of Leuctra (371), and were persuaded by Epaminondas to admit it as a member of the Boeotian confederation; but in 367 they accused it of conspiring against the democratical constitution, and burnt the city, putting the men to the sword and selling the women and children into slavery. It was re-built during the Phocian war, and made a Phocian stronghold; but at the end of the sacred war (346) it again fell into the hands of the Thebans, and was destroyed as before.
After the overthrow of the Thebans and Athenians at Clneronea (338) it was once more rebuilt, under the protection of Macedon; but it never regained any historic importance. ()r-chomenus was famous for its musicians, and for a festival in honor of the Graces in which poets and musicians from all parts of Greece took part. Remains have been discovered of the treasury of Atreus, and the pedestal of a tripod dedicated to the Graces, besides some ancient inscriptions in the Orchemenian-iEolic dialect, containing the digamma, which are now in the British museum.