ach vs AU, What's the Difference?

Which to use

“ach” and “AU” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.

#30,673
“ach” frequency rank: #6,867
“AU” frequency rank: 37540
confusion score

Side-by-Side Comparison

Feature	ach	AU
Definition	Any of several species of plants, such as smallage, wild celery, parsley.	Initialism of alopecia universalis.

Letter map: ach vs AU

Shared letters muted; letters that set ach and AU apart highlighted. Shared run: 1.

3 ch

ach

2 ch

Corpus notes: ach and AU

ach and AU are indexed as a confusable English pair. We have no recorded pronunciation or part of speech for both members, so the spelling overlap is what we can show you: they differ by 1 letter(s) in length. Our composite confusion score for this pair is 37540, derived from the frequency rank of both members and their visual similarity.

ach is recorded at frequency rank #30,673, classified as anoun, pronounced /æt͡ʃ/. AU is at rank #6,867, tagged as anoun.

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 37540, this pair ranks #293,700 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of ach vs AU

Shared letters: a. Private to "ach": ch. Private to "AU": u.

"ach" · 3 letters · shape VCC · "AU" · 2 letters · shape VV

Frequently Asked Questions

Is swapping "ach" for "AU" ever safe?

No. They differ by 1 letter(s) in length, but the dictionary glosses above give them different meanings, so swapping one for the other changes what the sentence says.

Frequency check: "ach" vs "AU" - which ranks higher?

"AU" is the more common of the two: it sits at frequency rank #6,867 in our English list, against #30,673 for "ach". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

Done with this confusable. These links stay specific to "ach" and "AU".

Full dictionary entry for "ach" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "AU" - compare definitions side by side with the headword page. Word entry
This pair ranks #293,700 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
"ach" and "AU" also get mixed up with nearby pairs, the highest-scored neighbour is "ach vs amb". Nearby pair

Confusion rank #293,700 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.