fax vs fui, What's the Difference?

Which to use

“fax” is a noun and “fui” is a verb - they look or sound alike but fill different roles in a sentence.

#14,370
“fax” frequency rank: #365
“fui” frequency rank: 14735
confusion score

Side-by-Side Comparison

Feature	fax	fui
Definition	aparelho transmissor e receptor de documentos em fac-símile	primeira pessoa do singular do pretérito perfeito simples do indicativo do verbo ir:

Where the eye mixes fax and fui

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

3 ch

fax

3 ch

fui

Look-alike desk: fax vs fui

These two trip readers on the page rather than in the ear: fax is /ˈfaks/ while fui is /ˈfuj/. 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 verb), which is usually the fastest check. Our composite confusion score for this pair is 14735, derived from the frequency rank of both members and their visual similarity.

fax is recorded at frequency rank #14,370, classified as anoun, pronounced /ˈfaks/. fui is at rank #365, tagged as averb, pronounced /ˈfuj/.

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 14735, this pair ranks #57,267 of 75,631 scored Portuguese confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of fax vs fui

Shared letters: f. Private to "fax": ax. Private to "fui": iu.

"fax" · 3 letters · shape CVC · "fui" · 3 letters · shape CVV

Frequently Asked Questions

Can "fax" and "fui" be used interchangeably?

No - they are not even the same part of speech. "fax" is a noun and "fui" a verb, so a sentence built for one is usually ungrammatical with the other.

Frequency check: "fax" vs "fui" - which ranks higher?

"fui" is the more common of the two: it sits at frequency rank #365 in our Portuguese list, against #14,370 for "fax". 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 "fax" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "fui" - compare definitions side by side with the headword page. Word entry
This pair ranks #57,267 of 75,631 scored Portuguese confusable pairs in this corpus vintage. Corpus statistics
"fax" and "fui" also get mixed up with nearby pairs, the highest-scored neighbour is "fava vs fax". Nearby pair

Confusion rank #57,267 of 75,631 scored Portuguese pairs, corpus vintage 2026-09-03, not spelling advice.