Which to use
“certain” is an adjective and “curtain” is a noun - they look or sound alike but fill different roles in a sentence.
- #707
- “certain” frequency rank
- #8,776
- “curtain” frequency rank
- 9483
- confusion score
Side-by-Side Comparison
| Feature | certain | curtain |
|---|---|---|
| Definition | Sure in one's mind, positive; absolutely confident in the truth of something. | A piece of cloth covering a window, bed, etc. to offer privacy and keep out light. |
Where the eye mixes certain and curtain
Muted = shared; highlighted = the visual trap. They share 6 letters in sequence.
Why the eye confuses certain with curtain
These two trip readers on the page rather than in the ear: certain is /ˈsɜː.tən/ while curtain is /ˈkɜːtn̩/. Spoken aloud the problem disappears. In writing it persists, because they differ by a single letter - e in “certain” becomes u in “curtain”, and the parts of speech differ too (adjective vs noun), which is usually the fastest check. Our composite confusion score for this pair is 9483, derived from the frequency rank of both members and their visual similarity.
certain is recorded at frequency rank #707, classified as anadj, pronounced /ˈsɜː.tən/. curtain is at rank #8,776, tagged as anoun, pronounced /ˈkɜːtn̩/.
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 9483, this pair ranks #497,179 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.
Orthographic DNA of certain vs curtain
Shared letters: acinrt. Private to "certain": e. Private to "curtain": u.
"certain" · 7 letters · shape CVCCVVC · "curtain" · 7 letters · shape CVCCVVC
Known mistypes of this pair
Frequently Asked Questions
Can "certain" and "curtain" be used interchangeably?
Which is more common, "certain" or "curtain"?
What to do next
Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.
- Full dictionary entry for "certain" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "curtain" - compare definitions side by side with the headword page. Word entry
- This pair ranks #497,179 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "certain" and "curtain" also get mixed up with nearby pairs, the highest-scored neighbour is "curtain vs Curtin". Nearby pair
- Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes
Confusion rank #497,179 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.