Caio

♂ Boy

Pronounced KY-oo /ˈkaɪ.u/Medium

Meaning: Welsh and Portuguese form of Gaius — an ancient Roman name, possibly 'to rejoice'Medium

In 30 seconds: An ancient Roman name in modern dress: Caio is the Welsh and Brazilian form of Gaius — possibly 'to rejoice'. Crisp, sunny, and surprisingly international, from Cardiff to Rio.

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Origin MediumLatin, Welsh

MeaningWelsh and Portuguese form of Gaius — an ancient Roman name, possibly 'to rejoice'

U.S. rank (2025)#3322 ↗ Rising

2025 U.S. births35 boys (0.00% of U.S. boys)

Peak year2023

Total births (all-time)≈ 722

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

Caio is the Welsh and Portuguese/Brazilian form of Gaius — an ancient Roman first name of uncertain meaning, often linked to Latin gaudere, 'to rejoice'. Popular in Wales and hugely so in Brazil, it is crisp, sunny, and cross-cultural; we note the meaning is debated.

In the U.S. it is rare, appearing in Welsh- and Brazilian-heritage families. Possibly 'to rejoice' at the root, ancient, and international.

Did you know? Caio is both a Welsh place and given name and one of Brazil's most popular boys' names — two distant corners of the world sharing the ancient Roman Gaius.

Overall data confidence 72%

Behind the Name — Caio — etymology

Variations

GaiusCaiKaio

Nicknames

Cai

Famous Bearers

★Caio Terra (1985-)
Brazilian jiu-jitsu world champion and coach
★Caio Castro (1989-)
Brazilian actor and television personality known for Globo network series

If you like Caio…

Gaius— the Roman source name

Cai— the short Welsh form

Leo— a fellow short, bright Latin name

Lucio— another Latin name

Claudio— shares Caio's Latin roots

Explore names like Caio

By themelatin welsh portuguese

By meaningSnow / Winter

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Frequently Asked

What does the name Caio mean?

Caio is a form of Gaius, an ancient Roman name possibly meaning 'to rejoice'; we note it's debated.

How do you pronounce Caio?

It's said KY-oo /ˈkaɪ.u/ — two syllables, stress on the first.

Is Caio a boy or girl name?

Caio is a boy's name.

How popular is Caio?

Caio is a rare name in the U.S., very popular in Brazil.