fonvsfuiWhat's the difference?

Quick tell: fon is a adjective, fui is a verb, so they fill different roles in a sentence.

Which to use

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

#44,372
“fon” frequency rank
#365
“fui” frequency rank
44737
confusion score

Side-by-Side Comparison

Feature fon fui
Definition relativo à etnia dos fons primeira pessoa do singular do pretérito perfeito simples do indicativo do verbo ir:

Where the eye mixes fon and fui

Muted = shared; highlighted = the visual trap. They share 1 letter in sequence. fon (CVC) and fui (CVV) run the same length but a different consonant-vowel pattern - the shape difference is usually the fastest tell.

3 ch
fon
3 ch
fui

Visual trap between fon and fui

These two trip readers on the page rather than in the ear: fon is /ˈfõ/ 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 (adjective vs verb), which is usually the fastest check. Our composite confusion score for this pair is 44737, derived from the frequency rank of both members and their visual similarity.

fon is recorded at frequency rank #44,372, classified as anadj, pronounced /ˈfõ/. 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 44737, this pair ranks #20,689 of 75,631 scored Portuguese confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of fon vs fui

Shared letters: f. Private to "fon": no. Private to "fui": iu.

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

Frequently Asked Questions

Do "fon" and "fui" mean the same thing in a sentence?
No - they are not even the same part of speech. "fon" is an adjective and "fui" a verb, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "fon" or "fui"?
"fui" is the more common of the two: it sits at frequency rank #365 in our Portuguese list, against #44,372 for "fon". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

What to do next

Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.

  • Full dictionary entry for "fon" 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 #20,689 of 75,631 scored Portuguese confusable pairs in this corpus vintage. Corpus statistics
  • "fon" and "fui" also get mixed up with nearby pairs, the highest-scored neighbour is "fern vs fon". Nearby pair

Confusion rank #20,689 of 75,631 scored Portuguese pairs, corpus vintage 2026-09-03, not spelling advice.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list