Which to use
“thirdly” is an adverb and “thirds” is a noun - they look or sound alike but fill different roles in a sentence.
- #26,995
- “thirdly” frequency rank
- #8,218
- “thirds” frequency rank
- 35213
- confusion score
Side-by-Side Comparison
| Feature | thirdly | thirds |
|---|---|---|
| Definition | In the third place; third in a row. | plural of third |
Where the eye mixes thirdly and thirds
Muted = shared; highlighted = the visual trap. They share 5 letters in sequence.
Visual trap between thirdly and thirds
These two trip readers on the page rather than in the ear: thirdly is /ˈθɜːdli/ while thirds is /θɜːdz/. Spoken aloud the problem disappears. In writing it persists, because they differ by 1 letter(s) in length, and the parts of speech differ too (adverb vs noun), which is usually the fastest check. Our composite confusion score for this pair is 35213, derived from the frequency rank of both members and their visual similarity.
thirdly is recorded at frequency rank #26,995, classified as anadv, pronounced /ˈθɜːdli/. thirds is at rank #8,218, tagged as anoun, pronounced /θɜːdz/.
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 35213, this pair ranks #313,933 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of thirdly vs thirds
Shared letters: dhirt. Private to "thirdly": ly. Private to "thirds": s.
"thirdly" · 7 letters · shape CCVCCCV · "thirds" · 6 letters · shape CCVCCC
Known mistypes of this pair
Frequently Asked Questions
Can "thirdly" and "thirds" be used interchangeably?
In ordinary English text, does "thirdly" or "thirds" show up more?
Useful next steps
Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.
- Full dictionary entry for "thirdly" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "thirds" - compare definitions side by side with the headword page. Word entry
- This pair ranks #313,933 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "thirdly" and "thirds" 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 #313,933 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.