Surah 2. Al-Baqara, Ayah 29

The term sama' ("heaven" or "sky") is applied to anything that is spread like a canopy above any other thing. Thus, the visible skies which stretch like a vault above the earth and form, as it were, its canopy, are called sama': and this is the primary meaning of this term in the Qur'an; in a wider sense, it has the connotation of "cosmic system". As regards the "seven heavens", it is to be borne in mind that in Arabic usage - and apparently in other Semitic languages as well - the number "seven" is often synonymous with "several" (see Lisan al-'Arab), just as "seventy" or "seven hundred" often means many or "very many" (Taj al-'Arus). This, taken together with the accepted linguistic definition that "every sama' is a sama' with regard to what is below it" (Raghib), may explain the "seven heavens" as denoting the multiplicity of cosmic systems. - For my rendering of thumma, at the beginning of this sentence, as "and", see surah {7}, first part of note [43].