onvsouiWhat's the difference?

Quick tell: on is a pronoun, oui is an adverb, so they fill different roles in a sentence.

Which to use

“on” is a pronoun and “oui” is an adverb - they look or sound alike but fill different roles in a sentence.

#29
“on” frequency rank
#132
“oui” frequency rank
161
confusion score

Side-by-Side Comparison

Feature on oui
Definition Pronom de la troisième personne du singulier. — Note d’usage : S’utilise pour désigner une ou des personnes indéfinies, en remplacement d’une forme passive. Mot utilisé pour apporter une réponse affirmative ou marquer l'accord sur une proposition. Il s’emploie aussi au début d’une phrase qui ne répond pas à une question exprimée ou au cours d’une phrase, pour marquer ou accentuer le caractère affirmatif de cette phrase. Il s’emploie dans le discours direct en réponse à une interrogation. Il est alors seul ou joint à des adverbes qui renforcent l’affirmation comme certes, vraiment, etc.

Where the eye mixes on and oui

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

2 ch
on
3 ch
oui

Spelling & Dictionary Insight

These two trip readers on the page rather than in the ear: on is \ɔ̃\ while oui is \wi\. 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 (pronoun vs adverb), which is usually the fastest check. Our composite confusion score for this pair is 161, derived from the frequency rank of both members and their visual similarity.

on is recorded at frequency rank #29, classified as apron, pronounced \ɔ̃\. oui is at rank #132, tagged as anadv, pronounced \wi\.

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 161, this pair ranks #440,037 of 440,172 scored French confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of on vs oui

Shared letters: o. Private to "on": n. Private to "oui": iu.

"on" · 2 letters · shape VC  ·  "oui" · 3 letters · shape VVV

Frequently Asked Questions

Can "on" and "oui" be used interchangeably?
No - they are not even the same part of speech. "on" is a pronoun and "oui" an adverb, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "on" or "oui"?
"on" is the more common of the two: it sits at frequency rank #29 in our French list, against #132 for "oui". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

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

Source: FrequencyWords open word-frequency list