S4 vs su, What's the Difference?

Which to use

“S4” is a noun and “su” is a verb - they look or sound alike but fill different roles in a sentence.

#32,174
“S4” frequency rank: #1,609
“su” frequency rank: 33783
confusion score

Side-by-Side Comparison

Feature	S4	su
Definition	Quatrième vertèbre sacrale (de haut en bas).	Participe passé masculin singulier du verbe savoir.

Where the spellings diverge

Shared letters are muted; the letters that actually set S4 and su apart are highlighted. They share 1 letter in sequence, which is exactly why the eye skips the difference.

2 ch

Spelling & Dictionary Insight

These two trip readers on the page rather than in the ear: S4 is \ɛs.katʁ\ while su is \sy\. Spoken aloud the problem disappears. In writing it persists, because they differ by a single letter - 4 in “S4” becomes u in “su”, and the parts of speech differ too (noun vs verb), which is usually the fastest check. Our composite confusion score for this pair is 33783, derived from the frequency rank of both members and their visual similarity.

S4 is recorded at frequency rank #32,174, classified as anoun, pronounced \ɛs.katʁ\. 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 33783, this pair ranks #288,308 of 440,172 scored French confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of S4 vs su

Shared letters: s. Private to "S4": -. Private to "su": u.

"S4" · 1 letters · shape C · "su" · 2 letters · shape CV

Frequency comparison

S4#32,174

su#1,609

Source: FrequencyWords open word-frequency list

Frequently Asked Questions

Can "S4" and "su" be used interchangeably?

No - they are not even the same part of speech. "S4" is a noun and "su" a verb, so a sentence built for one is usually ungrammatical with the other.

Which is more common, "S4" or "su"?

"su" is the more common of the two: it sits at frequency rank #1,609 in our French list, against #32,174 for "S4". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

Remembering S4 vs su

The fastest way to pick the right one every time.

Check the role first: if you need a noun, it's “S4”; for a verb, it's “su”.
See each word in full, definition, IPA, etymology and its other confusables. Full “S4” entry
Browse more pairs most likely to be confused. Most confusable