Which to use
“certain” is an adjective and “certainly” is an adverb - they look or sound alike but fill different roles in a sentence.
- #707
- “certain” frequency rank
- #1,069
- “certainly” frequency rank
- 1776
- confusion score
Side-by-Side Comparison
| Feature | certain | certainly |
|---|---|---|
| Definition | Sure in one's mind, positive; absolutely confident in the truth of something. | In a way which is certain; with certainty. |
Where the eye mixes certain and certainly
Muted = shared; highlighted = the visual trap. They share 7 letters in sequence.
Spelling & Dictionary Insight
These two trip readers on the page rather than in the ear: certain is /ˈsɜː.tən/ while certainly is /ˈsɜː.tn̩.li/. Spoken aloud the problem disappears. In writing it persists, because they differ by 2 extra letter(s) - “certain” sits inside “certainly”, and the parts of speech differ too (adjective vs adverb), which is usually the fastest check. Our composite confusion score for this pair is 1776, 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/. certainly is at rank #1,069, tagged as anadv, pronounced /ˈsɜː.tn̩.li/.
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 1776, this pair ranks #526,685 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.
Orthographic DNA of certain vs certainly
Shared letters: aceinrt. Private to "certain": -. Private to "certainly": ly.
"certain" · 7 letters · shape CVCCVVC · "certainly" · 9 letters · shape CVCCVVCCV