The term Allāh is most likely derived from a contraction of the Arabic article al- and ʾilāh “deity, god” to al-lāh meaning “the [sole] deity, God” (ho theos monos). Another theory traces the etymology of the word to the Aramaic Alāhā. Cognates of the name “Allāh” exist in other Semitic languages, including Hebrew and Aramaic. The corresponding Aramaic form is אֱלָהָא ˀĔlāhā in Biblical Aramaic and ܐܰܠܳܗܳܐ ˀAlâhâ or ˀĀlōho in Syriac. The term Allah is always used in the singular form; the plural form of the term does not exist in the Arabic language.
The contraction of al- and ʾilāh in forming the term Allāh (“the deity” in the masculine form) parallels the contraction of al- and ʾilāha in forming the term al-Lāt (“the deity” in the feminine form)