Cillian vs Thomas
Cillian and Thomascompared on official birth-registration statistics and Namewise's recorded data. This page states what each name's record shows — it never picks a winner or scores one name against the other.
Head to head
Ranks are only compared within one published list and one year. Two ranks from different years, from a boys' and a girls' list, or from different registrars are not comparable, so they are not placed side by side.
Northern Ireland · Boys
In 2024, Cillian was ranked #2 and Thomas #11 among boys in Northern Ireland.
Republic of Ireland · Boys
In 2025, Cillian was ranked #9 and Thomas #16 among boys in Republic of Ireland.
Scotland · Boys
In 2024, Cillian was ranked #83 and Thomas #20 among boys in Scotland.
England and Wales · Boys
In 2024, Cillian was ranked #177 and Thomas #26 among boys in England and Wales.
Cillian and Thomas over time
Cillian and Thomas appear together in 3 published lists, across 112 years of shared records. Thomas held the stronger position in more years in 3 of them, Cillian in 0.
The order between them changed and held in 2 of those lists — a change in that published list, never a claim that one name displaced the other.
Thomas reached its own highest recorded position earlier in 3 of those lists, and Cillian in none. Each position is a place inside its own list, so this compares when they peaked and never how high.
Counted list by list. Two names in the same published list are measured on the same scale in the same year, so those comparisons are real — but positions from different lists are not, so nothing here is combined into an overall standing.
How this pair is related
The relationship kinds these two qualify for, each under its own stated rule. Every one is drawn from a list they both appear in.
- One moved ahead of the other
In 2021, Cillian moved ahead of Thomas in Northern Ireland · Boys — #9 and #6 the year before became #8 and #11.
- Repeatedly exchanged positions
Cillian and Thomas changed places 5 times in Republic of Ireland · Boys between 1970 and 2025, ending at #9 and #16.
- Longest-running competitions
Cillian and Thomas were both ranked in Republic of Ireland · Boys for 55 years, from 1970 to 2025, ending at #9 and #16.
List by list
Republic of Ireland · Boys55 shared years, 1970–2025
Cillian held the stronger position in 9 of those years, Thomas in 46.
Highest recorded here: Cillian #4 in 2024, Thomas #6 in 1970.
The order changed in 2019: Cillian moved ahead. In 2018 they stood at #17 and #12; by 2019 that had become #17 and #18.
Most recent shared year, 2025: Cillian #9, Thomas #16.
England and Wales · Boys29 shared years, 1996–2024
Cillian held the stronger position in 0 of those years, Thomas in 29.
Highest recorded here: Cillian #177 in 2024, Thomas #2 in 1998.
The order between them never changed and held in this list.
Most recent shared year, 2024: Cillian #177, Thomas #26.
Northern Ireland · Boys28 shared years, 1997–2024
Cillian held the stronger position in 4 of those years, Thomas in 24.
Highest recorded here: Cillian #2 in 2024, Thomas #6 in 2020.
The order changed in 2021: Cillian moved ahead. In 2020 they stood at #9 and #6; by 2021 that had become #8 and #11.
Most recent shared year, 2024: Cillian #2, Thomas #11.
Two names moving past each other in a ranking is a fact about the ranking. Namewise does not claim one name displaced the other, that families chose between them, or that either influenced the other — none of that is in this data.
Side by side
| Field | Cillian | Thomas |
|---|---|---|
| Record type | Editorially researched profile | Editorially researched profile |
| Gender usage | male | male |
| Meaning | Probably from Old Irish 'cell' (church) combined with a diminutive suffix. | The Greek form of the Aramaic name meaning 'twin'. |
| Origin | Irish | Aramaic, via Greek |
| Pronunciation | Not yet recorded | /ˈtɑməs/ |
| Syllables | 2 | 2 |
| Common variants / nicknames | Not yet recorded | Not yet recorded |
| Recorded regional usage | GB-ENW, GB-NIR, GB-SCT, IE | AU-NSW, GB-ENW, GB-NIR, GB-SCT, IE, NO, NZ |
| Most recent popularity observation | Republic of Ireland · Boys #9 (2025) | New South Wales, Australia · Boys #13 (2025) |
| Pronunciation clarity (demonstration score) | Not yet recorded | 90/100 |
| Spelling simplicity (demonstration score) | 82/100 | 88/100 |
| International familiarity (demonstration score) | 100/100 | 100/100 |
| Data Confidence | medium | medium |
What the data shows
- Cillian is recorded with a Irish origin, while Thomas is recorded with a Aramaic, via Greek origin.
- Cillian and Thomas both have 2 syllables.
- Cillian's recorded meaning differs from Thomas's — see the table above for each.
- Both names have recorded usage in GB-ENW, GB-NIR, GB-SCT, IE.
How each name got here
Cillian
Popularity journey
First recorded1970
First recorded at #305 among boys in Republic of Ireland in 1970 — the earliest year that source publishes this name, not necessarily the earliest it was used.
Republic of Ireland · Boys
Highest recorded1997–2024
Highest recorded position: #2 among boys in Northern Ireland, in 2024 (recorded 1997–2024).
Northern Ireland · Boys
Most recent2025
Most recently recorded at #9 among boys in Republic of Ireland, in 2025.
Republic of Ireland · Boys
Thomas
Popularity journey
First recorded1945
First recorded at #177 among boys in Norway in 1945 — the earliest year that source publishes this name, not necessarily the earliest it was used.
Norway · Boys
Highest recorded1945–2025
Highest recorded position: #1 among boys in Norway, in 1974 (recorded 1945–2025).
Norway · Boys
Most recent2025
Most recently recorded at #13 among boys in New South Wales, Australia, in 2025.
New South Wales, Australia · Boys