Which to use
“third” is an adjective and “thirdly” is an adverb - they look or sound alike but fill different roles in a sentence.
- #483
- “third” frequency rank
- #26,995
- “thirdly” frequency rank
- 27478
- confusion score
Side-by-Side Comparison
| Feature | third | thirdly |
|---|---|---|
| Definition | The ordinal form of the cardinal number three; Coming after the second. | In the third place; third in a row. |
Where the eye mixes third and thirdly
Muted = shared; highlighted = the visual trap. They share 5 letters in sequence.
Why the eye confuses third with thirdly
These two trip readers on the page rather than in the ear: third is /θɜːd/ while thirdly is /ˈθɜːdli/. Spoken aloud the problem disappears. In writing it persists, because they differ by 2 extra letter(s) - “third” sits inside “thirdly”, and the parts of speech differ too (adjective vs adverb), which is usually the fastest check. Our composite confusion score for this pair is 27478, derived from the frequency rank of both members and their visual similarity.
third is recorded at frequency rank #483, classified as anadj, pronounced /θɜːd/. thirdly is at rank #26,995, tagged as anadv, pronounced /ˈθɜːdli/.
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 27478, this pair ranks #378,608 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of third vs thirdly
Shared letters: dhirt. Private to "third": -. Private to "thirdly": ly.
"third" · 5 letters · shape CCVCC · "thirdly" · 7 letters · shape CCVCCCV
Known mistypes of this pair
Frequently Asked Questions
Can "third" and "thirdly" be used interchangeably?
Which is more common, "third" or "thirdly"?
Useful next steps
Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.
- Full dictionary entry for "third" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "thirdly" - compare definitions side by side with the headword page. Word entry
- This pair ranks #378,608 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "third" and "thirdly" also get mixed up with nearby pairs, the highest-scored neighbour is "thickly vs thirdly". 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 #378,608 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.