Allāhi   Allaha   Allahu   Lillhi for Allah; due to; belongs to Lillāhi god (s)(diety) 'Ilahi God  of Mankind means Allah( The One) 'Ilahi Al-Nāsi   god (s)(diety) 'Ilāha

The word Allah is the greatest and most comprehensive of the divine names.  According to some scholars, it the 'Great Name' or 'Al-Ism al-a'zam.   According to the Tradition (Hadith), the Great Name Carries with it such benediction that a prayer is granted when this word has been uttered.  Report differ as to what this Great Name is)  The word 'Allah' refers to the Essence, and hence this name cannot be given to anyone except Allah.  This is why this word has neither a plural nor a dual, for Allah is One and has no associate.  In short, Allah is the name of the Ultimate Reality which comprehends in itself all the attributes of perfection, which is a Creator and Sustainers, Unique and Peerless.