No creature is there crawling on the earth, but its provision rests on Allah. 

He knows its lodging place and it repository. (11):6

Allah! There is no god but He,-the Living, the Self-subsisting, Eternal.
No slumber can seize Him nor sleep.
His are all things in the heavens and on earth.
Who is there can intercede in His presence except as He permitteth?
He knoweth what (appeareth to His creatures as) before or after or behind them.
Nor shall they compass aught of His knowledge except as He willeth.
His Throne doth extend over the heavens and the earth,
and He feeleth no fatigue in guarding and preserving them for He is the Most High, the Supreme (in glory). (Al-Baqara(2):255 YA)

Say, He is Allah, the One!
Allah is Absolute, Eternal, Unique, Self-Sufficient, Perfect, Independent,
the Uncaused Cause of all that exists, Besought of all .
He begets not, nor is He begotten.
And there is none that could be comparable unto Him.
(Al-Ikhlas(112):1-4 QXP)

The word "Allâh" is the perfect description of the "One God" of monotheism for Jews, Christians and Muslims.
"Allâh" is the same word used by Christian Arabs and Jewish Arabs in their Bible, centuries before Islam came and is still in use today. Muslims understand Allâh() as much as Allâh() wants them to by the guidance of the Qur'an. Allâh() exists without time and space. He is the creator of all that exists and isn't comparable to creation. Allâh's() actions, sight, hearing, knowledge are perfect as they are and aren't comparable as to humans.

Allâh() isn't to be assiciated with a gender, partnership, needs, physical image or any other type of limitation as it states in the Qur'an. We get a better understanding of Allâh() when we review the Ninety Nine Names/Attributes of Allâh mentioned in the Qur'an and their explanation.

Short review of other languages:

Aramaic : Alaaha

Hebrew: El, Elohim(pl), YHVH (Ar: Al-Hayy-ul Qayyum) (The Ever-Living, The Alive, The Self-Existing, The Self-Subsisting)

English: God (A 6th century word. No Prophet used this word to denote to the common God of Abrahamic faiths)

Definition of the word "Allâh" as it is in the Dictionary of the Qur'an by Abdul Mannaan Omar is as follows:

It is the proper noun applied to the Supreme Being, Who is the sole possessor of all perfect attributes,
Who is free from all defects and Who exists necessarily by Himself.
It is not a common noun.
All Divine attributes mentioned in the Holy Qur'an are qualities of the proper name Allâh.
No other language has a distinctive name for the Divine Being.
The names found in other languages are either attributive or descriptive and can be used in plural form,
but the word Allâh is never used for any other thing, being or deity. It is never used as a qualifying word.
The English word God,
which is the common Teutonic word for a personal object of religious worship applied to all superhuman beings of heathen mythologies who exercise power over nature and human being, can hardly be even an approximate substitute. Yahova means O That Person! While pronouncing the word Allâh the stress in accent is on the letters, L "

Thus Abdul Omar translates the word Allâh as: Proper name of the Almighty and Supreme Being.

The renowned theologian and heresiologist, Imam Abu IsHaq al-Isfarayani (d. 418/1027) remarked that, “All what theologians have said concerning the unity of God can be summed up in two statements: first, God is other than any concept that comes to mind. Second, while the essence of God is utterly unlike other essences, it is, nonetheless, not devoid of attributes.”

A Short Summary of our conception of Allâh maybe given as follows

Allâh: One True God.
Absolutely Unique and Alone in Lordship, Status etc.
We cannot comprehend Allah except which Allah has revealed
Word "Allâh" is Never Plural, doesn't have gender associated.
Allâh is not comparable or like any of the creation (i.e. Humans, Animals, Planets, Matter).
Allâh is was and will be Perfect in every way.
Allâh is the First and the Last. (Nothing Existed before Allah, neither anything will after)
Allâh is adored in worship,
Allâh creates all that exists,
Allâh has priority over all creation,
Allâh is lofty and hidden, (Not seen by mankind)
Allâh confounds all human understanding.

A Meeting With Allah!