The words "sky," "egg," and "window" were contributed to English by Old Norse, the language of the Vikings.
Sky → from Old Norse ský (meaning "cloud")
Egg → from Old Norse egg
Window → from Old Norse vindauga (vindr = "wind" + auga = "eye," meaning "wind-eye" or an opening for wind)
These words entered English during the Viking invasions (8th–11th centuries), when Old Norse heavily influenced Old English, especially in northern England.
