Which to use
“theirs” is a pronoun and “theses” is a noun - they look or sound alike but fill different roles in a sentence.
- #7,623
- “theirs” frequency rank
- #22,243
- “theses” frequency rank
- 29866
- confusion score
Side-by-Side Comparison
| Feature | theirs | theses |
|---|---|---|
| Definition | That or those belonging to them; the possessive case of they, used without a following noun. | plural of thesis |
Where the eye mixes theirs and theses
Muted = shared; highlighted = the visual trap. They share 4 letters in sequence. theirs (CCVVCC) and theses (CCVCVC) run the same length but a different consonant-vowel pattern - the shape difference is usually the fastest tell.
Visual trap between theirs and theses
These two trip readers on the page rather than in the ear: theirs is /ðɛəz/ while theses is /ˈθiːsiːz/. Spoken aloud the problem disappears. In writing it persists, because they share most of their letters but differ in 2 positions, and the parts of speech differ too (pronoun vs noun), which is usually the fastest check. Our composite confusion score for this pair is 29866, derived from the frequency rank of both members and their visual similarity.
theirs is recorded at frequency rank #7,623, classified as apron, pronounced /ðɛəz/. theses is at rank #22,243, tagged as anoun, pronounced /ˈθiːsiːz/.
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 29866, this pair ranks #359,386 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of theirs vs theses
Shared letters: ehst. Private to "theirs": ir. Private to "theses": -.
"theirs" · 6 letters · shape CCVVCC · "theses" · 6 letters · shape CCVCVC
Known mistypes of this pair
Frequently Asked Questions
Is swapping "theirs" for "theses" ever safe?
Which is more common, "theirs" or "theses"?
After this comparison
Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.
- Full dictionary entry for "theirs" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "theses" - compare definitions side by side with the headword page. Word entry
- This pair ranks #359,386 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "theirs" and "theses" also get mixed up with nearby pairs, the highest-scored neighbour is "tenses vs theses". 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 #359,386 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.