oncevsonlyWhich spelling fits?

Quick tell: once is a noun, only is an adjective, so they fill different roles in a sentence.

Which to use

“once” is a noun and “only” is an adjective - they look or sound alike but fill different roles in a sentence.

#11,815
“once” frequency rank
#11,816
“only” frequency rank
23631
confusion score

Side-by-Side Comparison

Feature once only
Definition Unité de mesure de la masse (système impérial britannique avoirdupois), qui vaut 28,3495231 grammes pour l'once commune → voir ounce. Ses symboles sont oz et ℥. L'once troy (troy ounce) équivaut pour sa part à 31,1034768 grammes. Seul.

Where the eye mixes once and only

Muted = shared; highlighted = the visual trap. They share 2 letters in sequence.

4 ch
once
4 ch
only

Visual trap between once and only

These two trip readers on the page rather than in the ear: once is \ɔ̃s\ while only is \ˈəʊn.li\. Spoken aloud the problem disappears. In writing it persists, because they share most of their letters but differ in 2 positions, and the parts of speech differ too (noun vs adjective), which is usually the fastest check. Our composite confusion score for this pair is 23631, derived from the frequency rank of both members and their visual similarity.

once is recorded at frequency rank #11,815, classified as anoun, pronounced \ɔ̃s\. only is at rank #11,816, tagged as anadj, pronounced \ˈəʊn.li\.

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 23631, this pair ranks #351,335 of 440,172 scored French confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of once vs only

Shared letters: no. Private to "once": ce. Private to "only": ly.

"once" · 4 letters · shape VCCV  ·  "only" · 4 letters · shape VCCV

Known mistypes of this pair

  • onceocne · oncce · onec · onnce
  • onlynoly · olny · onlly · onlyy · onnly · onyl

Frequently Asked Questions

Can "once" and "only" be used interchangeably?
No - they are not even the same part of speech. "once" is a noun and "only" an adjective, so a sentence built for one is usually ungrammatical with the other.
In ordinary French text, does "once" or "only" show up more?
"once" is the more common of the two: it sits at frequency rank #11,815 in our French list, against #11,816 for "only". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

What to do next

Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.

  • Full dictionary entry for "once" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "only" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #351,335 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
  • "once" and "only" also get mixed up with nearby pairs, the highest-scored neighbour is "och vs once". Nearby pair
  • Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes

Confusion rank #351,335 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