Which to use
“uncertain” is an adjective and “uncertainty” is a noun - they look or sound alike but fill different roles in a sentence.
- #7,299
- “uncertain” frequency rank
- #6,852
- “uncertainty” frequency rank
- 14151
- confusion score
Side-by-Side Comparison
| Feature | uncertain | uncertainty |
|---|---|---|
| Definition | Not certain; unsure. | Doubt; the condition of being uncertain or without conviction. |
Where the eye mixes uncertain and uncertainty
Muted = shared; highlighted = the visual trap. They share 9 letters in sequence. uncertain runs 9 letters (VCCVCCVVC) against uncertainty's 11 (VCCVCCVVCCV) - the length gap alone is often enough to separate them once you know to check it.
Look-alike desk: uncertain vs uncertainty
These two trip readers on the page rather than in the ear: uncertain is /ʌnˈsɜːtən/ while uncertainty is /ʌnˈsɜːtənti/. Spoken aloud the problem disappears. In writing it persists, because they differ by 2 extra letter(s) - “uncertain” sits inside “uncertainty”, and the parts of speech differ too (adjective vs noun), which is usually the fastest check. Our composite confusion score for this pair is 14151, derived from the frequency rank of both members and their visual similarity.
uncertain is recorded at frequency rank #7,299, classified as anadj, pronounced /ʌnˈsɜːtən/. uncertainty is at rank #6,852, tagged as anoun, pronounced /ʌnˈsɜːtənti/.
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 14151, this pair ranks #471,763 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.
Orthographic DNA of uncertain vs uncertainty
Shared letters: aceinrtu. Private to "uncertain": -. Private to "uncertainty": y.
"uncertain" · 9 letters · shape VCCVCCVVC · "uncertainty" · 11 letters · shape VCCVCCVVCCV
Known mistypes of this pair
- uncertain ← nucertain · ucnertain · unccertain · unceratin · uncerrtain · uncertainn · uncertani · uncertian
- uncertainty ← nucertainty · ucnertainty · unccertainty · unceratinty · uncerrtainty · uncertainnty · uncertaintty · uncertaintyy
Frequently Asked Questions
Is swapping "uncertain" for "uncertainty" ever safe?
Which is more common, "uncertain" or "uncertainty"?
After this comparison
Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.
- Full dictionary entry for "uncertain" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "uncertainty" - compare definitions side by side with the headword page. Word entry
- This pair ranks #471,763 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- 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 #471,763 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.