Origin: English, Welsh, Frisian
Meaning: a short form or nickname of names beginning with K such as Katherine (which has several possible meanings such as “pure, chaste” from the Greek katharos; or it could come from hekateros, “each of the two; singly”; or from Greek aikia meaning “torture”. It could also be a Coptic name meaning “my consecration of your name) or Kirk (meaning "church").
Kay is also from Welsh Cai or Cei, possibly derived from Roman Gaius, of uncertain etymology thought possibly related to Latin gaudere meaning "to rejoice".
It could also be a variant form of Kai, a Frisian diminutive of names such as Gerhard (meaning "brave spear" or "brave as a spear"), Nicolaas (the Dutch form of Nicholas meaning "victory of the people") , Cornelis (the Dutch form of Cornelius meaning "horn") or Gaius.
As a surname, Kay has several origins. It could be from Old Norse ka meaning "jackdaw". It could also be from Middle English caeg meaning "key", an occupational surname for a key-maker or a key bearer.
It could also be derived from Danish kei meaning "left", referring to someone who as lefthanded. Kay is also a habitational/occupational surname from Old French kay meaning "quay", referring to someone who lived near a quay or worked on one. The surname Kay could also be derived from Welsh name Cai.
Kay is also an English word, a short form of okay meaning everything is alright.
In the Arthurian legends, Kay is the foster-brother of Arthur and the biological son of Sir Ector.
- Cei (pronounced Kye)