Quick answer
Gaius is a boy name meaning "to rejoice".
Pronunciation: Latin /ˈɡaː.i.us/; English /ˈɡaɪ.əs/.
Meaning and history
Roman praenomen, or given name, of uncertain meaning. It is possibly derived from Latin gaudeo "to rejoice", though it may be of unknown Etruscan origin. This was a very common Roman praenomen, the most famous bearers being Gaius Julius Caesar, the great leader of the Roman Republic, and his adopted son Gaius Octavius (later known as Augustus), the first Roman emperor. This name also appears in the New Testament belonging to a bishop of Ephesus who is regarded as a saint.
Notes and context
Usage: ancient roman, biblical latin, biblical