Sayyid (also spelled Syed, Saiyed, Seyd, Sayed, Sayyad, Sayyed, Saiyid, Seyed, Said and Seyyed) (pronounced [səj.jɪd], Arabic: سيد; meaning Mister) (plural Sadah Arabic: سادة, Sāda(h), also spelled Sadat) is an honorific title denoting people (Sayyid for males, Sayyida for females) accepted as descendants of the Islamic prophet Muhammad through his grandsons, Hasan ibn Ali and Husayn ibn Ali, sons of Muhammad's daughter Fatimah and his son-in-law Ali (Ali ibn Abi Talib).
Women sayyids are given the titles Sayyida, Alawiyah, or Sharifa. In some regions of the Islamic world, such as in India, the descendants of Muhammad are given the title Amir or Mir, meaning commander, general, or prince. Children of a Sayyida mother but a non-Sayyid father are referred to as Mirza.
In the Arab world, sayyid is the equivalent of the English word "liege lord" or "master" when referring to a descendant of Muhammad, as in Sayyid Ali Sultan. The word sidi (from the contracted form sayyidī, 'my liege') is often used in Arabic.
Although not verified, many Arabic language experts state that it has its roots in the word Al Asad Arabic: الأسد meaning lion, probably because of the qualities of valour and leadership.