Abdurrahman — Name Meaning in Islam

Root: ر-ح-م (r-ḥ-m), "mercy" — and the root's first meaning is the womb, raḥim. ʿAbd ar-Raḥmān is a compound: ʿabd, servant, joined to ar-Raḥmān, the Most Merciful. The two words are one name.

From the same root: raḥma (mercy), raḥim (womb), ar-Raḥīm (the Merciful, the other of the pair opening every sūra), Raḥmān, Marḥūm.

The two mercies. Raḥmān and Raḥīm are not synonyms stacked for weight. The lexicographers distinguish them: Raḥmān is the intensive form, a mercy so wide it covers everyone without their asking; Raḥīm the sustained form, mercy directed and continuing. Ar-Raḥmān in particular is not used of any created thing.

Who carried it: Abd ar-Rahman ibn Awf, one of the earliest to accept Islam, a merchant who emigrated to Madina with nothing and rebuilt his trade there. The sources report the Prophet ﷺ naming Abdullah and Abd ar-Rahman as the names dearest to Allah, and several Companions were renamed to it.

Spellings: Abdurrahman, Abdul Rahman, Abd al-Rahman, Abdurrahman (Turkish), Abdurrahman/Abdurrachman (Indonesian), عبد الرحمن.

Pronunciation: ʿabd-ur-raḥ-MAAN — one name, not two words, with the ḥ deep in the throat.

Note: the ʿabd + name-of-Allah pattern only takes the names of Allah. Compounds with anything else are a different matter entirely.