Odour vs. Odor
“Odour” and “odor” are regional spellings of the same noun. “Odour” is standard in UK English, while “odor” is the standard US spelling.
Use “odour” for UK English and “odor” for US English.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| UK-English spelling for the smell noun | odour | Use “odour” when the governing variety is UK English. |
| US-English spelling for the same noun | odor | Use “odor” when the governing variety is US English. |
| quoted names, titles, brands, or source text | preserve the source spelling | Do not silently respell material that must remain verbatim. |
Quick tests
Meaning / construction test
Are you writing in a defined regional variety rather than reproducing fixed source wording?
If yes: Use “odour” for UK English and “odor” for US English, then stay consistent with that variety.
If no: If the wording is a quotation, proper name, title, or house-style exception, preserve the required form.
Caveat: The forms differ by regional spelling, not meaning. House style and verbatim source material can override a general regional default.
Examples
The room had a faint odour of paint.
“Odour” matches UK-English spelling.
The room had a faint odor of paint.
“Odor” matches US-English spelling.
The report reproduces the product name exactly as published.
Fixed source wording should be preserved rather than normalized by this regional spelling rule.
Further guidance
Core difference
The meaning is the same; the distinction is spelling convention.
Fast Test
Use “odour” in UK-oriented spelling and “odor” in US-oriented spelling, then stay consistent with the document’s regional style.
Usage Boundary
Do not present one form as universally correct and the other as an error; both are standard in their respective regional conventions.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- odour — Cambridge Dictionary (opens in a new tab)Cambridge University Press · Direct evidence for odour as the UK spelling in the smell sense.
- odor — Cambridge Dictionary (opens in a new tab)Cambridge University Press · Direct evidence for odor as the US spelling of odour.