sâda as in sādat Quraysh or the chiefs of Quraysh tribe) does not mean descendant of the prophet, for it existed before Islam.Hans Wehr Dictionary of Modern Written Arabic defines seyyid as master, chief, sovereign, or lord. It also denotes someone respected and of a status. Sayyid is also a common first name. Prominent figures are: Sayed Darwish, Sayyid Qutb, Sayed Mekawy. Although reliable statistics are unavailable, conservative estimates put the number of Sayyids in the tens of millions.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.Another term with a very similar meaning is Sharīf. History
The Sayyids are by definition a branch of Banu Hashim, which traces its lineage to Adnan, and therefore directly descends from Ishmael (Ismaeyl), and collaterally descends from his paternal half-brother Isaac (Ishaaq), the sons of Abraham (Ibrahim). Banū Hāshim (Arabic: بنو هاشم) is the clan of Muhammad, whose great-grandfather was Hashim ibn Abd Manaf, for whom the clan is named. Members of this clan are referred to as Hashemites. Descendants of Muhammad usually carry the titles Sayyid, Syed, Hashmi, Sayed or Sharif, or the Ashraf clan (synonymous to Ahl al-Bayt). Today, two sovereign monarchs – Abdullah II of Jordan and Muhammad VI of Morocco – and the former royal family of Libya are also considered to be a part of Banu Hashim.
Hence it is even problematic in a judicial point of view to call a patrilineal descendant of Ali Ibn Abi Talib a Sayyid, when he does not meet the above-mentioned criteria. See also
Family tree of Muhammad
Kohen, a similar status in Judaism
Sharīf, another term with a very similar meaning

Notes
References
Sources
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Sayad". Encyclopædia Britannica (11th ed.). Cambridge University Press. Van Arendonk, C.; Graham, W.A. (1960–2007). "Sharīf". In Bearman, P. J.; Bianquis, Th. ; Bosworth, C. E.; van Donzel, E.; Heinrichs, W. P. (eds.). Encyclopaedia of Islam, Second Edition.