Ad-Din ( , "(of) the religion/faith/creed") is a suffix component of some Arabic names in the construct case, meaning 'the religion/faith/creed', e.g. Saif ad-Din ( , "Sword of the Faith"). Varieties are also used in non-Arabic names throughout the Islamic world, It is used as a family name-suffix by some royal Muslim families, including the imperial Seljuks, Walashmas, and Mughals.
It is used as a traditional naming pattern among many South Asian Muslim families of various origins. Many Hyderabadi Muslim families also use it, and many of Hyderabadis belong to the Urdu-speaking Muhajir ethnic group of Pakistan, including them.
The Arabic spelling in its standard transliteration is . Due to the phonological rules involving the "sun letters" ( ), the Arabic letter () is an assimilated letter of the Arabic definite article (). This leads to the variant phonetic transliteration . The first noun of the compound must have the ending -u, which, according to the assimilation rules in Arabic (names in general are in the nominative case), assimilates the following a-, thus manifesting into in Classical and Modern Standard Arabic. However, all modern Arabic vernaculars lack the noun endings. Thus, the vowel of the definite article in them is pronounced in full as either a or e (the latter mostly in Maghreb and Egypt; as well as in Albania, Azerbaijan, Bosnia and Herzegovina, Kosovo and Turkey). At the same time, the Arabic short vowel u is rendered as short o in Iranian Persian, thus .
In practice, romanizations of Arabic names containing this element may vary greatly, including: , , , , , , , (particularly in English-speaking South, Southeast and East Asia) (particularly in French-speaking areas) (particularly in Azerbaijani and Turkish names) (particularly in Iranian Persian names) , (particularity in South Asia) Examples of names including this element are:
Aladdin Aftab al-Din Alimuddin Amin ud-Din Anwaruddin Asad ud-Din Awwal ud-Din Azharuddin Azim ud-Din Badr al-Din Baha' al-Din Burhan al-Din Fakhr al-Din Fariduddin Ghiyath al-Din Hamid al-Din Haqq ad-Din Hasan al-Din Hisham ud-Din Husam ad-Din Ikhtiyar al-Din Imad al-Din Ismat ad-Din Izz al-Din Jalal ad-Din Jamal ad-Din Kafil al-Din Kamal al-Din Khair ad-Din Majd ad-Din Mansur ad-Din Mizan ud-Din Mohy al-Din Mohyeddin Moinuddin Muhib ud-Din Mufiz-ud-Din Mu'in al-Din Mu'iz ad-Din Muslih ud-Din Najm al-Din Nasir al-Din Nazimuddin Nizam al-Din Nur al-Din Qamar ud-Din Qutb ad-Din Rashid al-Din Riazuddin Rukn al-Din Sa'd al-Din Sabr ad-Din Sadr al-Din Safi al-Din Saif al-Din Ṣalāḥ ad-Dīn Shams al-Din Sharaf al-Din Shihab al-Din Shujauddin Sirajuddin Taj al-Din Taqi al-Din Zahir al-Din Zamir al-Din Zayn ad-Din (or Zinedine) Ziauddin
Use of Uddin as surname In modern times in English-speaking environments, the name Uddin has sometimes been used as if it was a separate surname. An example is: Pola Uddin, Baroness Uddin (born 1959), British politician
Use of Eddine as surname
Ahmed Saad Eddine, Egyptian politician
See also al-Dawla Adin