Which to use
“certainly” is an adverb and “certainty” is a noun - they look or sound alike but fill different roles in a sentence.
- #1,069
- “certainly” frequency rank
- #9,295
- “certainty” frequency rank
- 10364
- confusion score
Side-by-Side Comparison
| Feature | certainly | certainty |
|---|---|---|
| Definition | In a way which is certain; with certainty. | The state of being certain. |
Where the eye mixes certainly and certainty
Muted = shared; highlighted = the visual trap. They share 8 letters in sequence.
Visual trap between certainly and certainty
These two trip readers on the page rather than in the ear: certainly is /ˈsɜː.tn̩.li/ while certainty is /ˈsɝtn̩ti/. Spoken aloud the problem disappears. In writing it persists, because they differ by a single letter - l in “certainly” becomes t in “certainty”, and the parts of speech differ too (adverb vs noun), which is usually the fastest check. Our composite confusion score for this pair is 10364, derived from the frequency rank of both members and their visual similarity.
certainly is recorded at frequency rank #1,069, classified as anadv, pronounced /ˈsɜː.tn̩.li/. certainty is at rank #9,295, tagged as anoun, pronounced /ˈsɝtn̩ti/.
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 10364, this pair ranks #492,715 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.
Orthographic DNA of certainly vs certainty
Shared letters: aceinrty. Private to "certainly": l. Private to "certainty": -.
"certainly" · 9 letters · shape CVCCVVCCV · "certainty" · 9 letters · shape CVCCVVCCV
Known mistypes of this pair
Frequently Asked Questions
Can "certainly" and "certainty" be used interchangeably?
In ordinary English text, does "certainly" or "certainty" show up more?
After this comparison
Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.
- Full dictionary entry for "certainly" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "certainty" - compare definitions side by side with the headword page. Word entry
- This pair ranks #492,715 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "certainly" and "certainty" also get mixed up with nearby pairs, the highest-scored neighbour is "certain vs certainty". 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 #492,715 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.