Why is the ninth month called September?
1550s, from Middle French sultan "ruler of Turkey" (16c.), from Arabic sultan "ruler, king, queen, power, dominion," from Aramaic shultana "power," from shelet "have power." His wife, mother, daughter, concubine, or sister is a sultana.
originally, according to the Qur'an, moral or spiritual authority; the term later came to denote political or governmental power and from the 11th century was used as a title by Muslim sovereigns. Mahmud of Ghazna (reigned AD 998-1030) was the first Muslim ruler to be called sultan by his contemporaries, and under the Seljuqs of Anatolia and Iran it became a regular title. Thereafter it was frequently conferred on sovereigns by the caliph (titular head of the Muslim community) and came to be used throughout the Islamic world.