The story
- Proto-Indo-European · inherited from*nókʷts“night”
- Proto-Indo-European · inherited from*septḿ̥“seven”
- Old English · inherited fromseofeniht
- Middle English · inherited fromseven-night
- English todaysevennight
From Middle English seven-night, sevenight, sevenyght [and other forms], from Late Old English seofeniht (compare seofonnihte (“seven days old; seven days long”, adjective)), from seofon (“seven”) (ultimately from Proto-Indo-European *septḿ̥ (“seven”)) + niht (“night; day (when computing spans of time)”) (ultimately from Proto-Indo-European *nókʷts (“night”)). Doublet of sennight.
Words from the same roots
Etymology from Wiktionary, CC BY-SA 4.0.