Cai

Cai is a Welsh name associated with the Arthurian hero known in English as Sir Kay. The Welsh form appears in early Arthurian tradition, giving the short name a substantial literary history. It is generally connected with the Roman name Caius or Gaius, whose exact original meaning is uncertain despite a traditional association with rejoicing.

Cei is another Welsh spelling, while Kay is the familiar English form of the character’s name. Cai also resembles names and surnames in other languages, including Chinese forms whose meanings depend on their characters. For a family choosing the Welsh name, the Arthurian connection provides the clearest context, keeping its specific tradition distinct from those unrelated uses of the same Latin letters.