All praise is due to Allah, and may peace and blessings be upon the Messenger of Allah. To proceed:
The Divine Name “Allah” is the proper name belonging exclusively to the One who alone is truly worthy of worship. It is the most specific and greatest of Allah’s Names. Scholars have differed as to whether it is derived from another word or is an original, underived proper name. As for the omission of the alif in its written form, this relates to Arabic orthography and the inherited written convention; it does not mean that the alif is absent from its pronunciation.
“Allah” is the Name of the One who alone is truly worthy of worship, and it is exclusive to Allah Almighty. In its true sense, it is not applied to anyone other than Him.
According to those who hold that the Name is derived, its meaning goes back to al-ilah: the deity who is worshipped and deserves worship. Thus, He is al-ma’luh, meaning the One who is worshipped, loved, and magnified, and who is worthy of every attribute of perfection.
For this reason, the Name “Allah” encompasses the meanings of the Most Beautiful Names and the Loftiest Attributes. Allah is Ar-Rahman, Ar-Rahim, Al-Malik, Al-Quddus, Al-‘Alim, Al-Hakim, As-Sami‘, Al-Basir, and possesses all other Attributes of perfection.
As-Sa‘di, may Allah have mercy on him, explained the meaning of the Name Allah as referring to the One who is worshipped and adored, who possesses divinity and the right to be worshipped by all of creation because of the Attributes of perfection He possesses. He alone deserves to be worshipped, praised, thanked, and magnified.
Scholars have differed concerning this matter, with two well-known opinions:
The first opinion: The Divine Name is not derived.
That is, it was originally established as a proper name for the Lord of the worlds and was not taken from another word.
According to this view, the letters alif and lam are part of the original structure of the word, and it is not meant that “al-” is simply an added definite article attached to another word.
This view has been attributed to a number of leading scholars of Arabic and other disciplines, including Al-Khalil and Sibawayh, and it was also chosen by Fakhr ad-Din ar-Razi.
One of the arguments offered by those who hold this opinion is that the Name “Allah” is exclusive to Him, whereas derived names normally share their basic meaning among more than one referent.
Another group of scholars held that the Divine Name is derived, although they differed regarding the root from which it is derived.
Among the best-known opinions are:
The meaning most closely connected to the concept of divinity is that which relates to worship and devotion, because an “ilah” is one who is worshipped, and Allah Almighty is the true God who alone deserves worship.
Among the verses cited in support of the derivation view is Allah’s saying:
“And He is Allah in the heavens and on the earth.”
[Al-An‘am 6:3]
And His saying:
“And He is the One who is God in the heaven and God on the earth.”
[Az-Zukhruf 43:84]
That is, He is the One worshipped in the heavens and the One worshipped on earth.
One of the most famous morphological explanations is that the original form of the word was “al-ilah”, after which omission and phonetic changes occurred until it became “Allah.”
According to this view, the hamzah was omitted and the two lams were assimilated, resulting in the familiar form:
Al-Ilah → Allah
Arabic linguists have mentioned several explanations for this derivation and morphological change. Therefore, one should not assert a single detailed morphological explanation with absolute certainty in light of this longstanding disagreement among leading linguists.
One may ask: if an alif is pronounced after the lam, why is the word written:
الله
rather than in a form that explicitly contains the alif corresponding to its pronunciation?
The answer is that the orthographic form of the word follows inherited Arabic writing conventions, in which the alif after the lam in the Divine Name is omitted in writing, as established in the written form of the Qur’an and Arabic orthography.
Linguists and commentators have mentioned various explanations for this omission. Among them is that the alif was omitted in writing to distinguish the Divine Name from certain other expressions, while other explanations have also been given.
The important point is that omitting the alif in writing does not mean omitting it in pronunciation. The word is pronounced:
Allah
with the known long vowel after the lam. Therefore, the written form cannot be used as evidence that the word contains no alif sound.
The written text of the Qur’an also has distinctive orthographic conventions known as the ‘Uthmani script (rasm ‘Uthmani), and written forms do not necessarily correspond letter-for-letter with modern orthography or pronunciation in every instance.
This question is connected to the disagreement concerning the origin of the word.
According to the view that “Allah” is derived from “al-ilah,” the discussion of “al-” relates to the original form of the word and the subsequent omission and assimilation.
According to the view that the Divine Name is an original, underived proper name, it is not correct simply to treat it as an ordinary word to which the Arabic definite article “al-” was added, as with “al-qamar” (the moon) or “al-kitab” (the book).
Therefore, the statement sometimes made that “Allah is just like al-qamar and al-kitab, with the definite article al- simply added to it” is an imprecise oversimplification of the issue, because the Divine Name has particular linguistic and religious significance, and scholars have fundamentally differed regarding its derivation and structure.
“Allah” is the proper Name of the One who alone is truly worthy of worship. It is the greatest of His Names and the most comprehensive in encompassing the meanings of perfection. Scholars have differed as to whether it is derived or underived.
According to the derivation view, one of the best-known opinions is that it comes from “al-ilah,” meaning the One who is worshipped, although other views regarding its etymological origin also exist.
As for the alif omitted in writing, this is part of the inherited Arabic orthographic convention and the written form of the Qur’an. It does not mean that the alif is absent in pronunciation; the word “Allah” is pronounced with the well-known long vowel.
And Allah knows best.