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Cassidy

♀ Girl

Pronounced KAS-ih-dee /ˈkæs.ɪ.di/High

Meaning: From Irish Gaelic Ó Caiside, a surname meaning 'descendant of Caiside,' where Caiside may derive from cas meaning 'curly-haired' or 'ingenious'; used as a given name particularly for girls in American EnglishHigh

In 30 seconds: Cassidy is a cheerful Irish surname-name meaning 'curly-haired,' transformed into a breezy American girls' name by country music and frontier legends. Three syllables of pure sunshine.
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Origin HighIrish Gaelic
MeaningFrom Irish Gaelic Ó Caiside, a surname meaning 'descendant of Caiside,' where Caiside may derive from cas meaning 'curly-haired' or 'ingenious'; used as a given name particularly for girls in American English
U.S. rank (2025)#541 ↘ Falling
2025 U.S. births558 girls (0.03% of U.S. girls)
Peak year1999
Total births (all-time)≈ 60,837

Popularity in the U.S. · SSA data

peak 199919692025

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

History & Origin

Cassidy is an Anglicisation of Irish Gaelic Ó Caiside, a clan surname from County Fermanagh. The root cas means 'curly' or 'ingenious,' possibly originally describing a curly-haired ancestor. The surname was carried to North America by Irish emigrants, and its use as a given name grew through the 20th century, initially for boys (in honor of Butch Cassidy and Hopalong Cassidy) and then shifting strongly toward girls.

Cassidy as a girls' name surged in the 1990s and reached the U.S. top 100, bolstered by country singer David Cassidy's fame and by the general trend toward Irish surname-names. It has declined somewhat from its peak but remains a well-recognized, friendly choice in the top 500. The nickname Cass offers easy informal use.

Did you know? Butch Cassidy — the legendary outlaw born Robert LeRoy Parker — took his alias from his associate Mike Cassidy, making Cassidy one of the most storied surname-names of the American West.
Overall data confidence 87%
Behind the Name — Cassidy — etymology and historyU.S. Social Security Administration — popularity data

Variations

KassidyCassady

Nicknames

CassCassieCaz

Famous Bearers

  • ★David Cassidy (1950–2017)
    American actor and singer, teen idol known for The Partridge Family, whose fame popularized the name.

If you like Cassidy…

Kennedy— shares the Irish surname-name heritage and the same spirited, three-syllable energy
Briar— nature-infused girls' surname-name with the same breezy, outdoorsy Americana feel
Piper— two-syllable Irish-influenced surname-name equally popular as a girls' choice
Finley— Irish surname-name with the same friendly, Celtic spirit and crossover appeal

Frequently Asked

What does the name Cassidy mean?

Cassidy comes from Irish Gaelic Ó Caiside meaning 'descendant of Caiside,' where cas means 'curly-haired' or 'ingenious.'

How do you pronounce Cassidy?

It is said KAS-ih-dee — three syllables, stress on the first.

Is Cassidy a boy or girl name?

Cassidy is used primarily as a girls' name in modern usage, though it was historically unisex as a surname-name.

How popular is Cassidy?

Cassidy reached the U.S. top 100 in the 1990s and remains in the top 500. It is most popular among parents who love Irish surname-names.