Allah

The name "Allah" is combination of the two arabic words , 'Al ' and  'ilah' . 'Al' means  'The' and 'ilah' means 'God'. these two words come together and refer to 'The God'  which implies 'The Only God' or ''The Only True God''. Nothing else can be called Allaah. The term has no plural or gender . This show its uniqueness when compared with the word 'god' which can be manipulated and made to plural (i.e gods) or feminine (i.e goddess)
whereas the word "Allaah" is unique .So we muslims prefer calling Allaah - The One and Only True God

Short poem :
Allaah is One
Related to None
Allah is One !
No father , No mother
No sister , No brother
No daughter , No son
Allaah is One !