Allah (; Arabic: ٱللَّٰه, romanized: Allāh, IPA: [ʔaɫ.ɫaːh] (listen)) is the common Arabic word for God. In the English language, the word generally refers to God in Islam. The word is thought to be derived by contraction from al-ilāh, which means "the god", and is linguistically related to the Aramaic words Elah and Syriac ܐܲܠܵܗܵܐ (ʼAlāhā) and the Hebrew word El (Elohim) for God.

The word Allah has been used by Arabic people of different religions since pre-Islamic times. The pre-Islamic Arabs worshipped a supreme deity whom they called Allah, alongside other lesser deities. Muhammad used the word Allah to indicate the Islamic conception of God. Allah has been used as a term for God by Muslims (both Arab and non-Arab), Judaeo-Arabic-speaking Jews, and even Arab Christians after the term "al-ilāh" and "Allah" were used interchangeably in Classical Arabic by the majority of Arabs who had become Muslims. It is also often, albeit not exclusively, used in this way by Bábists, Baháʼís, Mandaeans, Indonesian and Maltese Christians, and Sephardi Jews, as well as by the Gagauz people. Similar usage by Christians and Sikhs in Peninsular Malaysia has recently led to political and legal controversies.