ace vs AU, What's the Difference?

Which to use

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

#5,930
“ace” frequency rank: #6,867
“AU” frequency rank: 12797
confusion score

Side-by-Side Comparison

Feature	ace	AU
Definition	A playing card showing a single pip, typically the highest or lowest ranking card in a game.	Initialism of alopecia universalis.

Letter map: ace vs AU

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

3 ch

ace

2 ch

Pair insight - ace / AU

ace 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 12797, derived from the frequency rank of both members and their visual similarity.

ace is recorded at frequency rank #5,930, classified as anoun, pronounced /eɪs/. 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 12797, this pair ranks #479,512 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of ace vs AU

Shared letters: a. Private to "ace": ce. Private to "AU": u.

"ace" · 3 letters · shape VCV · "AU" · 2 letters · shape VV

Frequently Asked Questions

Is swapping "ace" 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.

In ordinary English text, does "ace" or "AU" show up more?

"ace" is the more common of the two: it sits at frequency rank #5,930 in our English list, against #6,867 for "AU". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Useful next steps

Pair "ace" vs "AU" is on the table, pick a follow-up below.

Full dictionary entry for "ace" 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 #479,512 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
"ace" and "AU" also get mixed up with nearby pairs, the highest-scored neighbour is "amb vs AU". Nearby pair

Confusion rank #479,512 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.