[starbase]

'Allah' means 'the god', and is completely equivalent to the Greek 'ho theos', meaning 'the god', with the definite article giving the same sense as the English capital letter in 'God', indicating the unique deity.

I see, then what was the moon god in Mecca's name? Or was there no moon god involved in Mohammedanism?

[The_Reader_David]

I mean the 'al ilah', elided to 'allah' means 'the god' in Arabic, and is used by Arabic speakers of all religions as an equivalent of the English 'God' (with the capital).

It may well be that adherents of a pre-Islamic Meccan lunar deity regarded their false god as preminent among the gods, and used 'the god' to refer to him. But this practice is irrelevant to the usage of the word in Arabic.

What is peculiar about Mohammedan usage (linguistically, leaving aside their host of false doctrines) is that they assume Allah is the proper name of the unique deity, and will not translate the word when when speaking other languages. Christians will say 'Allah' in Arabic to refer to the Holy Trinity, but will say 'God' when speaking English, "ho theos" when speaking Greek, "Le Dieu" when speaking French, etc.