Cassidy
Feminine · “descendant of Caiside”
Cassidy is given to both — 60,848 girls and 3,735 boys since 1880. See Cassidy as a boy nameSee other names given to both
Cassidy began as an Irish family name — Ó Caiside, the people of Caiside — carried out of Fermanagh and into American English, where it was picked up first by cowboys and then by children. It arrived on the American charts alongside the great Western about Butch Cassidy and the Sundance Kid, and it has three easy syllables that land on the first and skip lightly off the last.
How old is the name Cassidy?
Cassidy first appears in US birth records in 1969 — 56 years ago. The typical Cassidy alive today was born around 2001, making them about 24 years old. About 60,000 people named Cassidy are estimated to be alive in the US today.
When was the name Cassidy most popular?
Cassidy peaked in 1999, reaching #99 nationally. Today it ranks #541, 442 places below that high. See the whole 1999 chart.
Cassidy appears on these lists:
Where it comes from
From Caiside to Cassidy
The story of Cassidy
The Cassidys were an Irish family of Fermanagh, hereditary physicians to the Maguire lords there, and their surname — Ó Caiside — traveled with Irish emigration into English-speaking countries. In America the name became a fixture of Western storytelling: the outlaw Robert LeRoy Parker took Butch Cassidy as his alias, and the late-1960s film about him and the Sundance Kid put the word in front of an enormous audience. Cassidy entered American birth records as a given name in the wake of that film, joined the wave of surname-names given to girls through the 1980s and 1990s, and has been easing gently back down from its high point since.
Meaning
descendant of Caiside; from Irish cas, 'curly-haired'
The surname Ó Caiside means 'descendant of Caiside', and the personal name Caiside is built on the Irish word cas, 'curly' — so the sense reaching back through it is 'curly-haired one'.
How the name formed
- Caiside
- Ó Caiside
- Cassidy
Related forms: Ó Caiside · Ní Chaiside · Caiside
Pronouncing Cassidy
KASS-ih-dee
Stress on the first syllable, the middle one very light. English speakers read it correctly on sight; the Irish original, Ó Caiside, sounds close to oh-KASH-ih-djeh.
Nicknames for Cassidy
Moderate
What the data says
146 years of official birth records
The long climb, and where it stands now
The same years in position rather than babies
- First recorded
- 1969
- Most girls named
- 19993,395 — the highest on record
- Peak rank
- #99reached in 1999
- Change vs 2024
- −13.6%558 in 2025, from 646
Rank is a position, a count is a headcount, and they move independently — a name can hold its rank while the number of babies behind it falls. Source: U.S. Social Security Administration.
Cassidy in other languages
The same name elsewhere
- Ó Caiside in Irish — related form
- Ní Chaiside in Irish — related form
- Caiside in Irish — related form
Strongest US states over the last decade: California, Texas, Pennsylvania.
Cassidys among us
people named Cassidy are estimated to be alive in the US today
About 1 girl in 2,880 born in 2025 was named Cassidy
Estimated from SSA birth records and published actuarial life tables. Method
Spellings of Cassidy
- #541
- Cassidy on the 2025 chart
- #367
- counting every spelling
The SSA counts spellings, not names. Cassidy went to 558 girls in 2025, but Kassidy and Kassidi are the same name said out loud. Together the 3 spellings went to 813, which makes it the 367th most-given girls’ name of the year — 174 places above the chart.
About 1 girl in 1,977 born in 2025 was given one of these spellings — against 1 in 2,880 for Cassidy itself.
Spellings are grouped by a fixed rule that folds interchangeable English spellings of one sound (ck/k, ph/f, x/ks, a non-initial y for i) and keeps vowels apart, so Sean and Shawn stay separate names. It errs towards splitting: a family here is never larger than the truth. SSA national data, 2025. Method
Is it right for you
What happens to a name after it peaks
The Lola test
Every popular name lives one long story — a climb, a peak, a slow settling back. Cassidy's later chapters haven't been written yet, so we borrowed them: Lola climbed just as high around 1904, and its whole arc is on record. Line the two peaks up, and Lola's path sketches the road Cassidy is walking now.
Cassidy is coming down from a big peak (#99 in 1999). This is the stretch of the cycle where a name starts to sound like the decade it ruled.
A scored estimate from 146 years of naming cycles — not a prophecy. Great names outlive statistics. How this is scored
Where Cassidy is headed
Cassidy should hold steady through 2030 — the curve is flat, and flat curves are the most predictable kind.
High confidence — fitted on official counts through 2025.
A damped-trend projection of the official birth data — a sketch of momentum, not a promise. Every name's forecast, ranked.
Cassidy beside its neighbors
The names ranked closest to Cassidy in 2025, in babies rather than position — the bars are to scale.
US girls given each name in 2025.
The trade-off
- One standard spelling that almost everyone reads and writes correctly on the first try, backed by a surname long familiar in English.
- Ready-made short forms — Cass and Cassie — both of which already work as names on their own.
- A documented Irish family line behind it, which matters to parents who want an ancestral rather than an invented name.
- Common enough to be recognized everywhere, uncommon enough now that a child is unlikely to share it in a classroom.
- The best-known bearer of the name in American memory is an outlaw, and Butch Cassidy is still the first association for many people. It is affectionate rather than damaging, but it will come up.
- Surname-names ending in -y for girls — Cassidy among them — carry a fairly clear sense of when they were fashionable, so the name reads as belonging to a particular stretch of decades rather than as timeless.
- Because Cass and Cassie are shared with Cassandra, expect people to guess wrong about the full name, and expect Cassidy to be misheard as Cassandra now and then.
- It came from a surname, so it still travels to boys in small numbers; a girl named Cassidy will meet occasional assumptions either way, most often on paper.
Nobody names a baby alone.
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What they receive
Someone added a name to your list
Cassidy
Feminine · #541 in the U.S.
Frequently asked
- How many Cassidys are there in the world?
- No country counts the world's names, so there is no worldwide figure — anyone quoting one is estimating. About 60,000 people named Cassidy are estimated to be alive in the US today.
- How do you spell Cassidy?
- Cassidy is the most-used spelling in US records — 558 of the 813 babies given the name in 2025. The others recorded are Kassidy and Kassidi.
- How popular is the name Cassidy in 2025?
- Cassidy ranks #541 among US girl names in 2025, with 558 babies given the name.
- How rare is the name Cassidy?
- About 1 in every 2,880 US girls born in 2025 was named Cassidy — 558 in all.
- Will my child share the name Cassidy with classmates?
- Cassidy will almost certainly be the only one in school.
Ranked beside Cassidy
Names sitting at a similar level of popularity right now.
April#542 · Heaven#543 · Zahra#538 · Lenora#538 · Priscilla#544 · Daleyza#538 · Everlee#545 · Jazlyn#537
Looking for what else is popular rather than what resembles Cassidy? See the current top 100.
Choosing between Cassidy and another name?
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US figures from the Social Security Administration. 1880–2025. Data & methodology
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