Roman Names, Latin Names, Twilight Names

English speaking countries

Gaius or Caius was a common Roman praenomen (given name) of uncertain derivation.
It has been suggested it might relate to the Latin 'gaudere', "to rejoice".
It might also be linked to an Etruscan phrase, or to the Greek 'Gaia'.

It was used among the Romans as a firstname, with examples such as Gaius Julius Caesar and Gaius Caligula. It is mentioned in the Bible and is the name of a saint as well.

Caius is now considered a variant of Gaius, but was probably the original spelling. At the time the letter C, which occupies in the Roman alphabet the place of the Greek Gamma, was in some cases pronounced [G].

Caius (pronounced "Keys") is also the common short name for Gonville and Caius College, Cambridge, England.