Kaius

♂ Boy

Pronounced KY-us /ˈkaɪ.əs/High

Meaning: Rejoice; possibly from Latin Gaius (of uncertain meaning, possibly from gaudere: to rejoice) — a K-spelling variant of Caius/GaiusMedium

In 30 seconds: A K-spelling variant of Caius/Gaius, the ancient Roman praenomen meaning 'rejoice.' Julius Caesar's praenomen was Gaius — so Kaius connects directly to one of Rome's most iconic names.

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Origin MediumLatin, Greek

MeaningRejoice; possibly from Latin Gaius (of uncertain meaning, possibly from gaudere: to rejoice) — a K-spelling variant of Caius/Gaius

U.S. rank (2025)#1029 ↗ Rising

2025 U.S. births216 boys (0.01% of U.S. boys)

Peak year2025

Total births (all-time)≈ 2,009

Popularity in the U.S. · SSA data

U.S. births per year (Social Security Administration, 1880–present). Pink marker = peak year.

SSA data updated May 2026. How we source & verify this data.

History & Origin

Kaius is a K-spelling of Caius/Gaius, from the ancient Roman praenomen of uncertain etymology, possibly from Latin gaudere (to rejoice). Gaius Julius Caesar, Gaius Octavius (Augustus), and Gaius Marius were among the most famous Romans with this first name.

Kaius ranked #1134 for boys in 2024.

Did you know? Julius Caesar's full name was Gaius Julius Caesar — Gaius/Caius being his praenomen (first name). The Roman naming system assigned praenomina, nomina (clan names), and cognomina (personal names), and Gaius was one of the most common Roman praenomina.

Overall data confidence 80%

Behind the Name — Caius — Latin etymologyU.S. Social Security Administration — popularity data

Variations

CaiusGaiusKai

Nicknames

Kai

Famous Bearers

★Gaius Julius Caesar (100–44 BCE)
Roman general and statesman whose conquest of Gaul and crossing of the Rubicon transformed Rome. His praenomen (first name) was Gaius.

If you like Kaius…

Caius— the classical Latin spelling of the same Roman praenomen

Cassius— Roman praenomen-style name with the same ancient Latin gravitas

Maximus— Roman cognomen name with the same imperial authority

Julius— Roman nomen with the same classical first-name-of-Caesar tradition

Explore names like Kaius

By themelatin two-syllable roman ancient k-spelling

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Frequently Asked

What does the name Kaius mean?

Kaius is a K-spelling of Caius/Gaius, the ancient Roman praenomen possibly meaning 'rejoice.' Julius Caesar's first name was Gaius.

How do you pronounce Kaius?

It's said KY-us — two syllables, stress on the first.

Is Kaius a boy or girl name?

Kaius is used as a boys' name.

How popular is Kaius?

Kaius ranked #1134 for U.S. boys in 2024.