Ad-Din (Arabic:الْدِّينad-dīn[ædˈdiːn], "(of) the religion/faith/creed") is a suffix component of someArabic names in theconstruct case, meaning 'the religion/faith/creed', e.g. Saif ad-Din (Arabic:سيف الدّينSayf ad-Dīn, "Sword of the Faith"). Varieties are also used in non-Arabic names throughout the Muslim world, It is used as a family name-suffix by some royal Muslim families, including the imperialSeljuks,Walashmas,Mughals, and the nobleAlviHyderabadi families.
The Arabic spelling in its standard transliteration isal-Din. Due to the phonological rules involving the "sun letter" (حرف الشّمسيّةhurfu ’sh-Shamsiyyah), the Arabic letterد (dāl) is an assimilated letter of theArabic definite articleال (al). This leads to the variant phonetic transliterationad-Din. The first noun ofthe compound must have the ending -u, which, according to the assimilation rules in Arabic (names in general are in the nominative case), assimilates the followinga-, thus manifesting intoud-Din inClassical andModern 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 eithera ore (the latter mostly inMaghreb andEgypt). At the same time, the Arabic short vowelu is rendered as shorto in Persian, thusod-din.
In practice, romanizations of Arabic names containing this element may vary greatly, including:
Examples of names including this element are:
In modern times in English-speaking environments, the name Uddin has sometimes been used as if it was a separate surname. An example is: