Which to use
“io” is a noun and “ISF” is a name - they look or sound alike but fill different roles in a sentence.
- #23,588
- “io” frequency rank
- #17,462
- “ISF” frequency rank
- 41050
- confusion score
Side-by-Side Comparison
| Feature | io | ISF |
|---|---|---|
| Definition | Septième lettre de l’alphabet cyrillique, ё. | Impôt déclaratif payé par les personnes physiques, célibataires ou en couple, possédant un patrimoine imposable dont la valeur nette est supérieure à un seuil fixé par la loi. |
Where the eye mixes io and ISF
Muted = shared; highlighted = the visual trap. They share 1 letter in sequence.
Why the eye confuses io with ISF
These two trip readers on the page rather than in the ear: io is \jo\ while ISF is \i ɛ.s‿ɛf\. 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 (noun vs name), which is usually the fastest check. Our composite confusion score for this pair is 41050, derived from the frequency rank of both members and their visual similarity.
io is recorded at frequency rank #23,588, classified as anoun, pronounced \jo\. ISF is at rank #17,462, tagged as aname, pronounced \i ɛ.s‿ɛf\.
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 41050, this pair ranks #235,914 of 440,172 scored French confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of io vs ISF
Shared letters: i. Private to "io": o. Private to "ISF": fs.
"io" · 2 letters · shape VV · "ISF" · 3 letters · shape VCC
Frequently Asked Questions
Do "io" and "ISF" mean the same thing in a sentence?
In ordinary French text, does "io" or "ISF" show up more?
What to do next
Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.
- Full dictionary entry for "io" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "ISF" - compare definitions side by side with the headword page. Word entry
- This pair ranks #235,914 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
- "io" and "ISF" also get mixed up with nearby pairs, the highest-scored neighbour is "io vs isi". Nearby pair
Confusion rank #235,914 of 440,172 scored French pairs, corpus vintage 2026-09-03, not spelling advice.