Which to use
“O'Neill” and “O'Reilly” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.
- #11,572
- “O'Neill” frequency rank
- #18,638
- “O'Reilly” frequency rank
- 30210
- confusion score
Side-by-Side Comparison
| Feature | O'Neill | O'Reilly |
|---|---|---|
| Definition | A surname from Irish. | A surname from Irish [in turn originating as a patronymic] from Reilly. |
Where the eye mixes O'Neill and O'Reilly
Muted = shared; highlighted = the visual trap. They share 6 letters in sequence. O'Neill runs 6 letters (VCVVCC) against O'Reilly's 7 (VCVVCCV) - the length gap alone is often enough to separate them once you know to check it.
Look-alike desk: O'Neill vs O'Reilly
A purely visual mix-up. O'Neill (/əʊˈniːl/) and O'Reilly (/əˈɹaɪli/) are said differently, so reading them aloud is the quickest way to catch the wrong one. On the page they stay close: they differ by 1 letter(s) in length. Our composite confusion score for this pair is 30210, derived from the frequency rank of both members and their visual similarity.
O'Neill is recorded at frequency rank #11,572, classified as aname, pronounced /əʊˈniːl/. O'Reilly is at rank #18,638, tagged as aname, pronounced /əˈɹaɪli/.
Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.
With a confusion score of 30210, this pair ranks #356,474 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of O'Neill vs O'Reilly
Shared letters: eilo. Private to "O'Neill": n. Private to "O'Reilly": ry.
"O'Neill" · 6 letters · shape VCVVCC · "O'Reilly" · 7 letters · shape VCVVCCV
Frequently Asked Questions
Can "O'Neill" and "O'Reilly" be used interchangeably?
Which is more common, "O'Neill" or "O'Reilly"?
After this comparison
Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.
- Full dictionary entry for "O'Neill" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "O'Reilly" - compare definitions side by side with the headword page. Word entry
- This pair ranks #356,474 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "O'Neill" and "O'Reilly" also get mixed up with nearby pairs, the highest-scored neighbour is "O'Neil vs O'Neill". Nearby pair
Confusion rank #356,474 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.