sky
The expanse of air above the earth; the heavens.
Etymology
Modern English sky comes from Old Norse ský "cloud," borrowed into English during the Viking Age, from Proto-Germanic *skiwją, from PIE *skewH- meaning "to cover, to conceal." The original meaning was "cloud" — a covering — and the shift to mean the entire overhead expanse happened in English during the 13th century. Before this borrowing, Old English used heofon (heaven) and lyft (the air, which survives in loft and aloft). The same PIE root gave Latin obscūrus "dark, hidden" (literally "covered over"), producing English obscure. It also connects to Latin scūtum "shield" (a covering) and possibly to English shoe through the idea of a foot-covering. Old English scēo "cloud" from the same root was displaced by the Norse form. The connection between clouds, covering, and sky reveals how the word travelled from "that which hides" to "the dome above."
The Journey: *skewH- → sky
*skewH-
*skiwją
ský
sky
sky
Cognates Across Languages
These words in other languages descend from the same PIE root *skewH-. They are not borrowings but independent inheritances from a common ancestor.
| Language | Word | Meaning |
|---|---|---|
| Old Norse | ský | cloud |
| Latin | obscūrus | dark, covered |
| Old English | scēo | cloud |
| Swedish | sky | cloud (still!) |
| Gothic | skuggwa | mirror, shadow |
Did You Know?
In Swedish, sky still means "cloud," not "sky" — preserving the original Norse meaning. English borrowed the word from Vikings but shifted its meaning upward. Meanwhile, the word obscure comes from the same PIE root: the sky, to its speakers, was originally "the covering" — and something obscure is literally "covered over."