Added 7 October 2026
key
/kiː/ symbol
In Latin: clāvis Wiktionary
symbol Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about key at Wordnik → Where our words come from →
noun
-
An object designed to open and close a lock or to activate or deactivate something, especially a length of metal inserted into a narrow opening on the lock to which it is matched (keyed).
This key is to the backdoor.
-
A card or fob that electronically signals a lock to open.
My hotel room key is a card.
- A piece of information (e.g., a password or passphrase) used to encode or decode a message or messages.
adjective
verb
- To fit (a lock) with a key.
- To fit (pieces of a mechanical assembly) with a key to maintain the orientation between them.
- To mark or indicate with a symbol indicating membership in a class.
Origin
From Middle English keye, kaye, keiȝe, from Old English cǣġ (“key, solution, experiment”) (whence also Scots key and kay (“key”)), from Anglo-Frisian Proto-West Germanic *kaiju, of uncertain origin. The only sure cognates are Saterland Frisian Koai (“key”), West Frisian kaai (“key”), and North Frisian kai, koie (“key”). Possibly from Proto-Germanic *kēgaz, *kēguz (“stake, post, pole”), from Proto-Indo-European *ǵogʰ-, *ǵegʰ-, *ǵegʰn- (“branch, stake, bush”), which would make it cognate with Middle Low German kāk (“whipping post, pillory”), and perhaps to Middle Dutch keige (“javelin, spear”) and Middle Low German keie, keige (“spear”).
From Wiktionary, via Kaikki.org (CC BY-SA)