boy's name
Cillian
KIL-ee-an
- Origin Irish
- Gender Boy
- Syllables 3
- Letters 7
- Popularity Top 1000 (Ireland)
- Births on record 17,776
the United States
#507
2025 births
Cillian is a boy's name of Irish origin. Sources disagree about its meaning: most give "little church," from cill, while others derive it from ceallach, strife. It ranked ninth in Ireland in 2025 and second in Northern Ireland.
- Cillian is a name of Irish origin.
- Peaked in Ireland in 2007, when 377 babies were given the name.
- Its usage has held steady over the past decade in Ireland.
- Today about 1 in 166 babies in Ireland is given this name.
- First appears in birth records in 1970.
Cillian over time
Births per decade in Ireland, 1970s to 2020s. The striped bar is the 2020s, still in progress — it covers 2020 to 2025, not a full ten years.
Show the numbers
| Decade | Births |
|---|---|
| 1970s | 81 |
| 1980s | 314 |
| 1990s | 757 |
| 2000s | 2,156 |
| 2010s | 3,209 |
| 2020s (to 2025) | 1,852 |
What Cillian means
Cillian most likely means little church or, read another way, one associated with a church — from cill, a church or monastic cell, with a diminutive ending. A competing derivation takes it from ceallach, contention or strife, which gives the near-opposite sense of a warrior.
Where Cillian comes from
The dominant reading takes Cillian from the Irish cill, a church or monastic cell, a word borrowed from the Latin cella and visible in hundreds of Irish place names beginning Kil-. With the diminutive -ín the sense is something like little church, understood as a person belonging to one. The rival derivation is from ceallach, strife, and reference works divide between the two without either being settled — which is why the same name is glossed as "little church" on one site and "war, strife" on the next. The best-known bearer is Saint Cillian, a seventh-century Irish missionary who evangelised Franconia and was martyred at Würzburg, where he remains the patron saint and where his feast is still kept in July.
Cillian in use
Cillian ranked ninth in Ireland in 2025 with 271 births, but its strongest showing is in Northern Ireland, where it stood second in 2024. It is also the Irish name that has traveled furthest recently: 507 in the United States and 217 in England and Wales, with an American peak in 2024 that coincides with the actor Cillian Murphy's Academy Award for Oppenheimer in March of that year.
How popular is Cillian?
In 2025, Cillian was given to 271 babies in Ireland, ranking #9 that year. It is a well-established, commonly used name.
Where Cillian is used
Irish figures withhold any name given to fewer than three babies in a year, so a gap means the name fell below that floor rather than went unused. The Central Statistics Office began recording the síneadh fada in 2018, so accented and unaccented spellings are counted separately from that year on. Data & sources.
How Cillian is spelled
Birth registers count each spelling separately, so every one has its own ranking.
| Spelling | What it is | Births on record |
|---|---|---|
| Cillían | Cillían is a rare spelling of Cillian, written with a fada and recorded 22 times, mostly in Ireland. | 22 |
Names that peaked alongside Cillian
These names rose and fell in the same era, which is why they tend to sound like they belong together.
Parents who like Cillian also like
Names whose popularity has risen and fallen in step with Cillian over the last century — the same taste, a different name.
Cillian in other languages
The same name as it is spelled elsewhere — not shortenings, and not different names that merely sound alike. Each one has its own record here.
Sibling names for Cillian
Names from the same era that won't rhyme or share an initial with Cillian — the two things that make a sibling set grate.
Common questions about Cillian
What does the name Cillian mean?
Most sources give "little church," from the Irish cill. Others derive it from ceallach, strife.
Why do sources disagree about what Cillian means?
Two plausible roots exist — cill, a church, and ceallach, strife — and neither derivation is settled, so reference works split between them.
How do you pronounce Cillian?
KIL-ee-an. The C is hard, as in kill, not soft as in cinema.
Is Cillian the same name as Killian?
Yes. Killian is the anglicized spelling of the same Irish name.
How popular is the name Cillian?
In 2025, Cillian was given to 271 babies in Ireland, ranking #9 that year. It is a well-established, commonly used name.
Is Cillian a girl's or a boy's name?
Cillian is given almost entirely to boys in birth records.
How many syllables are in Cillian?
Cillian has 3 syllables.
When was Cillian most popular?
Cillian peaked in 2007, when 377 babies were given the name. Its usage has held steady over the past decade.
Is Cillian a good name?
That is not something records can settle, but they can tell you what you would be choosing. Cillian currently ranks #2 in Ireland. Its usage has held steady over the past decade. Everything else — how it sounds with your surname, who it reminds you of — is yours.