What does Allah mean?

The word is the all encompassing name of God, it carries all means known and unknown.

As for the word Allah coming from the the word Deity with the definite article attached, this is false. As whenever the word has ya attached to it would be Ya halu then the word, if it followed this pattern. When ya is attached to it, the word stays the same. So it cannot be this.

Allah is word if recited bring relief to the reciter, I have tried it myself many times.

There is also a link here, for an article written by Dr Umar Abdullah about the name God.

http://www.nawawi.org/downloads/article2.pdf