Usual English form of Dorothea. The name was not used in the Middle Ages, but was taken up in the 15th century and became common thereafter. It was borne by the American film star Dorothy Lamour (1914–1996, born Dorothy Kaumeyer).
Turkish: from the Turkish personal name Osman, Turkish form of Arabic ῾Uthmān. This was the name of the third of the ‘rightly guided’ khalifs (ruled 644–656), one of the ten Companions of the Prophet Muhammad, to whom he gave the good news of entering into paradise.