SFvssuWhat's the difference?

Quick tell: SF is a adjective, su is a verb, so they fill different roles in a sentence.

Which to use

“SF” is an adjective and “su” is a verb - they look or sound alike but fill different roles in a sentence.

#15,503
“SF” frequency rank
#1,609
“su” frequency rank
17112
confusion score

Side-by-Side Comparison

Feature SF su
Definition De science-fiction, relatif à la science-fiction. Participe passé masculin singulier du verbe savoir.

Letter map: SF vs su

Shared letters muted; letters that set SF and su apart highlighted. Shared run: 1.

2 ch
SF
2 ch
su

Grammar separator: SF vs su

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: SF is anadjective and suaverb. On the page they differ by a single letter - f in “SF” becomes u in “su”. Our composite confusion score for this pair is 17112, derived from the frequency rank of both members and their visual similarity.

SF is recorded at frequency rank #15,503, classified as anadj. 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 17112, this pair ranks #384,740 of 440,172 scored French confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of SF vs su

Shared letters: s. Private to "SF": f. Private to "su": u.

"SF" · 2 letters · shape CC  ·  "su" · 2 letters · shape CV

Frequently Asked Questions

Is swapping "SF" for "su" ever safe?
No - they are not even the same part of speech. "SF" is an adjective and "su" a verb, so a sentence built for one is usually ungrammatical with the other.
In ordinary French text, does "SF" or "su" show up more?
"su" is the more common of the two: it sits at frequency rank #1,609 in our French list, against #15,503 for "SF". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Useful next steps

You've compared "SF" and "su". Here's where to go from here.

  • Full dictionary entry for "SF" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "su" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #384,740 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
  • "SF" and "su" also get mixed up with nearby pairs, the highest-scored neighbour is "SF vs suu". Nearby pair

Confusion rank #384,740 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