1. Quran is about the recitation. However it is commonly used for the written Book.
The recitation of the word and its writing are two distinct realities. However in this case the written book is recited so much and is memorised by so many people that when the word Quran is used it can commonly mean the written book by way of majaz. Majaz can mean allegory, figure of speech, rhetoric etc.
The literal use of a word and its allegorical use is found in Arabic and many other languages.
An example of a figure of speech from English literature would be:
“For who would bear the whips and scorns of time, …” Shakespeare’s Hamlet

2. AlGhazali mentions ‘seven ahruf‘ (سبعة أحرف) in his definition which I choose in the translation as ‘seven recitations’. That was taken from a hadith that “the Quran was revealed in seven ahruf” but its meaning is highly disputed. Some say it is the seven recitations and this is what I think alGhazali meant. Others say it is more than seven recitations. Furthermore, some give it an esoteric meaning. But that is a hadith. It is not Quran.
One should note that the Arabic word sabaa (سبعة) can have more than one meaning. Of these meanings is seven and completeness.
Having said that the foremost authority on Quranic recitations is Muhammad bin Muhammad aDimashqui, famous as Ibn alJazri, [born 751 Hijra / 1350 CE in Damascus and died 833 Hijra / 1429 CE in Shiraz] detailed in his works the ten famous recitations.
There are only ten famous recitations of the whole Quran that survived.

3. Some would mention in the definition the content of that which is to be defined. This is not accepted in definitions.
This means that when you are asked about defining a word, you are not asked to enumerate all or some of its content.
That the Quran has stories of the old, legislation etc. is true but it is part of its content. Hence that should not be in the definition.
So ‘what is the Quran ?’ is clearly a different question from ‘what is the content of the Quran?