The story
- Proto-Indo-European · derived from*kagʰyóm“enclosure”
- Proto-Celtic · derived from*kagyom“pen, enclosure”
- Gaulish · derived from*kagyum
- Old French · derived fromkay
- Middle English · inherited fromkay
- English todayquay
The current spelling replaced the spelling key in the 1690s to emulate the spelling but (at least originally) not the pronunciation of the equivalent modern French quai. From Middle English kay, key, kaye, keye, from Old French kay, cail, from Gaulish *kagyum, cagiíun (“enclosure”), from Proto-Celtic *kagyom (“pen, enclosure”) (compare Welsh cae (“field”)), from Proto-Indo-European *kagʰyóm (“enclosure”). Doublet of hedge and hey (“choreographic figure”).
Words from the same roots
Proto-Indo-European*kagʰyóm all →
Etymology from Wiktionary, CC BY-SA 4.0.