MAALIK - Lexicography
In one reading (Qira'at) the word is ‘Malik’, which means king, i.e., He (Allah) is not only Owner-Master but King also, Ever All-Powerful, Ever All-Sovereign. (Taisirul Quran, Hafiz Atiqur-Rahmaan Kailani).

In "Tirmizii", “Al-Malik” has been included in the `Asmaaul Husnaa' of Allah. In this context see:
"Malikinnaas" : King of the mankind,
"Allaahul Malikul Haqqu" Allah, the True King.
"Wa tabaarakallazii lahuu mulkus-samaawaati wal ardz wa maa baina humaa":
And Blessed is He (Allah), to Whom belongs
the kingdom of the heavens and the earth and all that is between them”.

"Tabaarakallazii Biyadihil Mulk": (Surah Mulk 67-1)
“Blessed is He (Allah), in Whose hands is the Dominion,
and He, over all things, has Ever All-Power”
Maalik: Owner, Master with all Authority and Powers to forgive, grant Clemency in His Infinite Wisdom’: not a mere judge bound to award punishment to the guilty:
“Say: `To whom belongs all that is in the heavens and the earth’?
Say: To Allah, He has inscribed for Himself Mercy.
That He will gather you together for the Day of Judgement,
there is no doubt whatsoever.
It is they who have lost their own souls, that they will not believe.”

Maalik is proprietor (also): (Wortabet)
J.G.Hava and F. Steingass in their respective Arabic-English Dictionaries, have given one of the meanings as follows:

Malk : Knead the dough well, Make the dough to rise.
"The word Maalik has been derived from the root "M I L K" (i.e. letters: MIIM , LAAM , KAAF ), which signifies possessing a thing in such a manner that one has the right and power to dispose of it as one likes.(see Qamuus). The word Diin signifies requital . So, the phrase "Master of the Day of Requital" implies total mastery on the Day of Requital….the mastery over every thing that exists will belong to Allah Alone.". (Page 66, Maariful Quran , M.M.M.Shafi.)

The word Malikun (King) is used for the king of humanbeings (e.g. `Malikin-naas' in 114-1) but it is not used for man as malikul-ashiyaa, i.e ‘king of things’ (because he is not the king of creations.)
(Mufridatul Quran, Imam Raghib Isfahani)
Malikun:
(i) One who practically possesses and rules:

"She said: `Verily, kings, when they enter a town,
they despoil it and make the most honourable among its people the lowest,
And thus they do" 27-34

(ii) One who possesses the power and ability to rule:
"ja-ala fiikum anbiyaa-a wa ja-alakum maluukan" 5-20
“He (Allah) made prophets among you, and made you kings”

Since the kingdom and the dominion all belong truly to Allah Alone, the Quran explains as under:
"Whatsoever is in the heavens and whatsoever is in the earth glorifies Allah.
His is the dominion , and to Him belong all the praises and thanks,
And He is able to do all things" :

" Say: `O Allah, Possessor of the kingdom,
You give the kingdom to whom You will,
And You take the kingdom from whom you will"

Allah's dominion and administration extends over all universes:

"Thus did We (Allah) show Ibrahim, the kingdom of the heavens and the earth,
that he be one of those who have Faith with certainty."

"Do they not look in the dominion of the heavens and the earth,
and all things that Allah has created"

Allah's control as the King extends not merely over physical existence of a thing but over its faculty and functionality also in all respects, so much so that ‘creation’ has no independent control of its own even over its own composition:

"Yet they have taken besides Him (Allah) other gods,
who created nothing but are themselves created,
and possess no control of hurt nor benefit for themselves,
and possess no power (of) death nor (of) life, nor of raising the dead"

"Say: 'I possess no power over benefit or hurt to myself, except as Allah wills"

For more details see Mufridatul Quran, Imam Raghib Isfahani. For different shades of meaning and usage see pages 788-789, Al-Muajimul Mufaharis, Muhammad Fawaad Abdul Baqi. Following comparisons and synonyms may make the meaning of Maalik clearer:
Maalik : The Possessor who has the Power to dispose of.
Rabb : The Owner who trains, sustains and grows.
Ahl : Household and owner of the house.
(Mutaraadifatul Quran, Abdur-Rahmaan Kailani).