sad vs si, What's the Difference?

Which to use

“sad” is an adjective and “si” is a conjunction - they look or sound alike but fill different roles in a sentence.

#26,525
“sad” frequency rank: #46
“si” frequency rank: 26571
confusion score

Side-by-Side Comparison

Feature	sad	si
Definition	Triste.	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.

Where the eye mixes sad and si

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

3 ch

sad

2 ch

Why the eye confuses sad with si

These two trip readers on the page rather than in the ear: sad is \sæd\ while si is \si\. 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 (adjective vs conjunction), which is usually the fastest check. Our composite confusion score for this pair is 26571, derived from the frequency rank of both members and their visual similarity.

sad is recorded at frequency rank #26,525, classified as anadj, pronounced \sæd\. si is at rank #46, tagged as aconj, 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 26571, this pair ranks #334,171 of 440,172 scored French confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of sad vs si

Shared letters: s. Private to "sad": ad. Private to "si": i.

"sad" · 3 letters · shape CVC · "si" · 2 letters · shape CV

Frequently Asked Questions

Can "sad" and "si" be used interchangeably?

No - they are not even the same part of speech. "sad" is an adjective and "si" a conjunction, so a sentence built for one is usually ungrammatical with the other.

In ordinary French text, does "sad" or "si" show up more?

"si" is the more common of the two: it sits at frequency rank #46 in our French list, against #26,525 for "sad". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

Useful next steps

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

Full dictionary entry for "sad" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "si" - compare definitions side by side with the headword page. Word entry
This pair ranks #334,171 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
"sad" and "si" also get mixed up with nearby pairs, the highest-scored neighbour is "sad vs suu". Nearby pair

Confusion rank #334,171 of 440,172 scored French pairs, corpus vintage 2026-09-03, not spelling advice.