C1vsciWhat's the difference?

Quick tell: C1 is a noun, ci is an adverb, so they fill different roles in a sentence.

Which to use

“C1” is a noun and “ci” is an adverb - they look or sound alike but fill different roles in a sentence.

#12,528
“C1” frequency rank
#264
“ci” frequency rank
12792
confusion score

Side-by-Side Comparison

Feature C1 ci
Definition Niveau de langue correspondant à un niveau expérimenté (autonome) : personne capable de comprendre des textes longs et exigeants et saisir des significations implicites ; s’exprimer spontanément et couramment sans trop devoir chercher ses mots ; utiliser la langue de façon efficace et souple dans la vie sociale, professionnelle ou académique ; s’exprimer sur des sujets complexes de façon claire et bien structurée et manifester son contrôle des outils linguistiques d'organisation, d’articulation et de cohésion du discours. ou (Utilisé uniquement dans les compositions, pas utilisé isolément) Ici.

Where the eye mixes C1 and ci

Muted = shared; highlighted = the visual trap. They share 1 letter in sequence.

2 ch
C1
2 ch
ci

Look-alike desk: C1 vs ci

These two trip readers on the page rather than in the ear: C1 is \se.œ̃\ while ci is \si\. Spoken aloud the problem disappears. In writing it persists, because they differ by a single letter - 1 in “C1” becomes i in “ci”, and the parts of speech differ too (noun vs adverb), which is usually the fastest check. Our composite confusion score for this pair is 12792, derived from the frequency rank of both members and their visual similarity.

C1 is recorded at frequency rank #12,528, classified as anoun, pronounced \se.œ̃\. ci is at rank #264, tagged as anadv, pronounced \si\.

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 12792, this pair ranks #403,742 of 440,172 scored French confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of C1 vs ci

Shared letters: c. Private to "C1": -. Private to "ci": i.

"C1" · 1 letters · shape C  ·  "ci" · 2 letters · shape CV

Frequently Asked Questions

Do "C1" and "ci" mean the same thing in a sentence?
No - they are not even the same part of speech. "C1" is a noun and "ci" an adverb, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "C1" or "ci"?
"ci" is the more common of the two: it sits at frequency rank #264 in our French list, against #12,528 for "C1". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

What to do next

Eye-level mix-up between "C1" and "ci" is sorted above. Next: full entries or other pairs that share a letter shape.

  • Full dictionary entry for "C1" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "ci" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #403,742 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
  • "C1" and "ci" also get mixed up with nearby pairs, the highest-scored neighbour is "C1 vs CCE". Nearby pair

Confusion rank #403,742 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