"heofones," an ancient Anglo-Saxon word for heavens in the Beowulf
The modern English word heaven is derived from the earlier (Middle English) heven (attested 1159); this in turn was developed from the previous Old English form heofon. By about 1000, heofon was being used in reference to the Christianized "place where God dwells", but originally, it had signified "sky, firmament" (e.g. in Beowulf, c. 725). The English term has cognates in the other Germanic languages: Old Saxon heƀan "sky, heaven" (hence also Middle Low German heven "sky"), Old Icelandic himinn, Gothic himins; and those with a variant final -l: Old Frisian himel, himul "sky, heaven", Old Saxon and Old High German himil, Old Saxon and Middle Low German hemmel, Old Dutch and Dutch hemel, and modern German Himmel. All of these have been derived from a reconstructed Proto-Germanic form *hemina-. or *hemō.
The further derivation of this form is uncertain. A connection to Proto-Indo-European *ḱem- "cover, shroud", via a reconstructed *k̑emen- or *k̑ōmen- "stone, heaven", has been proposed. Others endorse the derivation from a Proto-Indo-European root *h₂éḱmō "stone" and, possibly, "heavenly vault" at the origin of this word, which then would have as cognates Ancient Greek ἄκμων (ákmōn "anvil, pestle; meteorite"), Persian آسمان (âsemân, âsmân "stone, sling-stone; sky, heaven") and Sanskrit अश्मन् (aśman "stone, rock, sling-stone; thunderbolt; the firmament"). In the latter case English hammer would be another cognate to the word.