fui vs fun, What's the Difference?

Which to use

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

#365
“fui” frequency rank: #16,068
“fun” frequency rank: 16433
confusion score

Side-by-Side Comparison

Feature	fui	fun
Definition	primeira pessoa do singular do pretérito perfeito simples do indicativo do verbo ir:	divertido

Where the eye mixes fui and fun

Muted = shared; highlighted = the visual trap. They share 2 letters in sequence.

3 ch

fui

3 ch

fun

Visual trap between fui and fun

These two trip readers on the page rather than in the ear: fui is /ˈfuj/ while fun is /fʌn/. Spoken aloud the problem disappears. In writing it persists, because they differ by a single letter - i in “fui” becomes n in “fun”, and the parts of speech differ too (verb vs adjective), which is usually the fastest check. Our composite confusion score for this pair is 16433, derived from the frequency rank of both members and their visual similarity.

fui is recorded at frequency rank #365, classified as averb, pronounced /ˈfuj/. fun is at rank #16,068, tagged as anadj, pronounced /fʌn/.

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 16433, this pair ranks #55,104 of 75,631 scored Portuguese confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of fui vs fun

Shared letters: fu. Private to "fui": i. Private to "fun": n.

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

Frequently Asked Questions

Is swapping "fui" for "fun" ever safe?

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

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

"fui" is the more common of the two: it sits at frequency rank #365 in our Portuguese list, against #16,068 for "fun". 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 "fui" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "fun" - compare definitions side by side with the headword page. Word entry
This pair ranks #55,104 of 75,631 scored Portuguese confusable pairs in this corpus vintage. Corpus statistics
"fui" and "fun" also get mixed up with nearby pairs, the highest-scored neighbour is "fern vs fun". Nearby pair

Confusion rank #55,104 of 75,631 scored Portuguese pairs, corpus vintage 2026-09-03, not spelling advice.