fouvsFSUWhat's the difference?

Quick tell: fou is a adjective, FSU is a name, so they fill different roles in a sentence.

Which to use

“fou” is an adjective and “FSU” is a name - they look or sound alike but fill different roles in a sentence.

#1,063
“fou” frequency rank
#30,171
“FSU” frequency rank
31234
confusion score

Side-by-Side Comparison

Feature fou FSU
Definition Qualifie une personne qui a perdu la raison, qui est atteinte d’aliénation mentale. Fédération française de syndicats de l’enseignement.

Letter map: fou vs FSU

Shared letters muted; letters that set fou and FSU apart highlighted. Shared run: 2.

3 ch
fou
3 ch
FSU

Grammar separator: fou vs FSU

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: fou is anadjective and FSUaname. On the page they differ by a single letter - o in “fou” becomes s in “FSU”. Our composite confusion score for this pair is 31234, derived from the frequency rank of both members and their visual similarity.

fou is recorded at frequency rank #1,063, classified as anadj, pronounced \fu\. FSU is at rank #30,171, tagged as aname.

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 31234, this pair ranks #305,087 of 440,172 scored French confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of fou vs FSU

Shared letters: fu. Private to "fou": o. Private to "FSU": s.

"fou" · 3 letters · shape CVV  ·  "FSU" · 3 letters · shape CCV

Frequently Asked Questions

Do "fou" and "FSU" mean the same thing in a sentence?
No - they are not even the same part of speech. "fou" is an adjective and "FSU" a name, so a sentence built for one is usually ungrammatical with the other.
In ordinary French text, does "fou" or "FSU" show up more?
"fou" is the more common of the two: it sits at frequency rank #1,063 in our French list, against #30,171 for "FSU". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

What to do next

Pair "fou" vs "FSU" is on the table, pick a follow-up below.

  • Full dictionary entry for "fou" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "FSU" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #305,087 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
  • "fou" and "FSU" also get mixed up with nearby pairs, the highest-scored neighbour is "Fee vs FSU". Nearby pair

Confusion rank #305,087 of 440,172 scored French pairs, corpus vintage 2026-09-03, not spelling advice.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list