Which to use
“acid” is an adjective and “acier” is a noun - they look or sound alike but fill different roles in a sentence.
- #43,247
- “acid” frequency rank
- #3,974
- “acier” frequency rank
- 47221
- confusion score
Side-by-Side Comparison
| Feature | acid | acier |
|---|---|---|
| Definition | Acide, aigre, sur, aigri, revêche, hargneux. | Alliage de fer et de carbone, dont la proportion de celui-ci ne dépasse pas 2 %, susceptible d’acquérir, par certains procédés, un grand degré de dureté. |
Where the eye mixes acid and acier
Muted = shared; highlighted = the visual trap. They share 3 letters in sequence. acid runs 4 letters (VCVC) against acier's 5 (VCVVC) - the length gap alone is often enough to separate them once you know to check it.
Look-alike desk: acid vs acier
These two trip readers on the page rather than in the ear: acid is \a.ˈʦid\ while acier is \a.sje\. 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 noun), which is usually the fastest check. Our composite confusion score for this pair is 47221, derived from the frequency rank of both members and their visual similarity.
acid is recorded at frequency rank #43,247, classified as anadj, pronounced \a.ˈʦid\. acier is at rank #3,974, tagged as anoun, pronounced \a.sje\.
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 47221, this pair ranks #188,584 of 440,172 scored French confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of acid vs acier
Shared letters: aci. Private to "acid": d. Private to "acier": er.
"acid" · 4 letters · shape VCVC · "acier" · 5 letters · shape VCVVC
Known mistypes of this pair
Frequently Asked Questions
Is swapping "acid" for "acier" ever safe?
Frequency check: "acid" vs "acier" - which ranks higher?
Useful next steps
Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.
- Full dictionary entry for "acid" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "acier" - compare definitions side by side with the headword page. Word entry
- This pair ranks #188,584 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
- "acid" and "acier" also get mixed up with nearby pairs, the highest-scored neighbour is "ACF vs acid". 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 #188,584 of 440,172 scored French pairs, corpus vintage 2026-09-03, not spelling advice.