an vs ao, What's the Difference?

Which to use

“an” is an adverb and “ao” is a contraction - they look or sound alike but fill different roles in a sentence.

#2,817
“an” frequency rank: #27
“ao” frequency rank: 2844
confusion score

Side-by-Side Comparison

Feature	an	ao
Definition	ligado, aceso:	contração da preposição a com o artigo definido o

Where the eye mixes an and ao

Muted = shared; highlighted = the visual trap. They share 1 letter in sequence.

2 ch

Visual trap between an and ao

These two trip readers on the page rather than in the ear: an is /an/ while ao is /aw/. Spoken aloud the problem disappears. In writing it persists, because they differ by a single letter - n in “an” becomes o in “ao”, and the parts of speech differ too (adverb vs contraction), which is usually the fastest check. Our composite confusion score for this pair is 2844, derived from the frequency rank of both members and their visual similarity.

an is recorded at frequency rank #2,817, classified as anadv, pronounced /an/. ao is at rank #27, tagged as acontraction, pronounced /aw/.

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 2844, this pair ranks #72,408 of 75,631 scored Portuguese confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of an vs ao

Shared letters: a. Private to "an": n. Private to "ao": o.

"an" · 2 letters · shape VC · "ao" · 2 letters · shape VV

Frequently Asked Questions

Is swapping "an" for "ao" ever safe?

No - they are not even the same part of speech. "an" is an adverb and "ao" a contraction, so a sentence built for one is usually ungrammatical with the other.

In ordinary Portuguese text, does "an" or "ao" show up more?

"ao" is the more common of the two: it sits at frequency rank #27 in our Portuguese list, against #2,817 for "an". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

What to do next

Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.

Full dictionary entry for "an" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "ao" - compare definitions side by side with the headword page. Word entry
This pair ranks #72,408 of 75,631 scored Portuguese confusable pairs in this corpus vintage. Corpus statistics
"an" and "ao" also get mixed up with nearby pairs, the highest-scored neighbour is "acs vs an". Nearby pair

Confusion rank #72,408 of 75,631 scored Portuguese pairs, corpus vintage 2026-09-03, not spelling advice.