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The short answer
Cillian is a masculine name used in Irish. Behind the Name describes it this way: "Probably from Old Irish cell meaning ‘church’ combined with a diminutive suffix. This was the name of a 7th-century Irish saint who evangelized in Franconia." It ranked #507 for boys in the United States in 2025.
Meaning and etymology
According to Behind the Name, probably from Old Irish cell meaning ‘church’ combined with a diminutive suffix. This was the name of a 7th-century Irish saint who evangelized in Franconia. The entry lists its usage as Irish.
Editorial confidence: likely
Popularity
Cillian ranked #507 for boys in the United States in 2025. The figure comes from the Social Security Administration's national file for that year.
| Region | Year | Rank | Source |
|---|---|---|---|
| United States | 2025 | #507 | ssa-2025 |
If you like this name
Names that Behind the Name files under the same origin (Irish) and that sit near Cillian in the 2025 American rankings.
Similar by origin
Frequently asked questions
What does the name Cillian mean?
Cillian means "church", according to Behind the Name.
Is Cillian a popular name?
Cillian ranked #507 for boys in the United States in 2025. (Social Security Administration data).
Is Cillian a boy's or a girl's name?
In the 2025 SSA data Cillian appears in the boys' list; Behind the Name labels it masculine.
Sources
- Behind the Name: Meaning, origin and history of the name Cillian — supports meaning, usage, pronunciation, variants.
- U.S. Social Security Administration: Popular Baby Names — national data, year of birth 2025 — supports popularity.
