Meaning and name origin
Caius \caius\ as a boy's name is pronounced keys. It is of Latin origin, and the meaning of Caius is "happy". Common Roman form of Gaius. This was the name of the infamous Roman emperor called Caligula, a nickname meaning "little boots". This referred to the minature soldier's footwear he wore when he was young. A 16th-century English physician endowed a college at Cambridge University called "Gonville and Caius".
Caius is not a popular first name for males and an equally uncommon surname or last name for all people (2000 U.S. Census).
Displayed below is a comparison of the popularity of the boy name Caius and its variant forms. The only popular variation form ranked in the Top 1000/100 is Kay. (2014 statistics).
Caius is also pronounced similarly to Cass. Like Caius, this name is not commonly used.