the.com/sleepover

means a social arrangement, usually for children or friends, in which guests stay overnight at someone's home, typically involving little actual sleep.

from A plain English compound of "sleep" and "over," in the sense of staying over at someone's place — the same "over" you hear in "stay over" or "come over." Both halves are old, homely Germanic words: "sleep" traces to Old English slǣpan, and "over" to ofer. The fused noun "sleepover" itself is comparatively recent, a 20th-century coinage that rose with the suburban childhood ritual it names.