Which to use
“si” is a conjunction and “su” is a verb - they look or sound alike but fill different roles in a sentence.
- #46
- “si” frequency rank
- #1,609
- “su” frequency rank
- 1655
- confusion score
Side-by-Side Comparison
| Feature | si | su |
|---|---|---|
| Definition | Dans le cas où, à condition que, supposé que. Note d’usage : Conjonction qui introduit une condition (suivie d’une conséquence) ou une supposition qui peut être supprimée en utilisant un conditionnel. | Participe passé masculin singulier du verbe savoir. |
Where the spellings diverge
Shared letters are muted; the letters that actually set si and su apart are highlighted. They share 1 letter in sequence, which is exactly why the eye skips the difference.
Spelling & Dictionary Insight
si and su form a confusable pair in the French index, two distinct headwords that are easily confused because they look alike, sound alike, or both. They differ by a single letter - i in “si” becomes u in “su” - close enough that the eye skips over the difference, far enough that meaning fully diverges. Our composite confusion score for this pair is 1655, derived from the frequency rank of both members and their visual similarity.
si is recorded at frequency rank #46, classified as aconj, pronounced \si\. su is at rank #1,609, tagged as averb, pronounced \sy\.
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 1655, this pair ranks #437,629 of 440,172 scored French confusable pairs - a relatively easy-to-tell-apart pair.
Frequency comparison
Frequently Asked Questions
Can "si" and "su" be used interchangeably?
Remembering si vs su
The fastest way to pick the right one every time.
- Check the role first: if you need a conjunction, it's “si”; for a verb, it's “su”.
- See each word in full, definition, IPA, etymology and its other confusables. Full “si” entry
- Browse more pairs most likely to be confused. Most confusable