favsfuiTell them apart

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

Which to use

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

#5,107
“fa” frequency rank
#852
“fui” frequency rank
5959
confusion score

Side-by-Side Comparison

Feature fa fui
Definition En solfeo, cuarta nota de la escala musical. Primera persona del singular (yo) del pretérito perfecto simple de indicativo de ser.

Where the eye mixes fa and fui

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

2 ch
fa
3 ch
fui

Visual trap between fa and fui

These two trip readers on the page rather than in the ear: fa is [ˈfa] while fui is [ˈfwi]. Spoken aloud the problem disappears. In writing it persists, because they differ by 1 letter(s) in length, and the parts of speech differ too (noun vs verb), which is usually the fastest check. Our composite confusion score for this pair is 5959, derived from the frequency rank of both members and their visual similarity.

fa is recorded at frequency rank #5,107, classified as anoun, pronounced [ˈfa]. fui is at rank #852, tagged as averb, pronounced [ˈfwi].

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 5959, this pair ranks #312,182 of 323,831 scored Spanish confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of fa vs fui

Shared letters: f. Private to "fa": a. Private to "fui": iu.

"fa" · 2 letters · shape CV  ·  "fui" · 3 letters · shape CVV

Frequently Asked Questions

Can "fa" and "fui" be used interchangeably?
No - they are not even the same part of speech. "fa" is a noun and "fui" a verb, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "fa" or "fui"?
"fui" is the more common of the two: it sits at frequency rank #852 in our Spanish list, against #5,107 for "fa". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

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 "fa" 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 #312,182 of 323,831 scored Spanish confusable pairs in this corpus vintage. Corpus statistics
  • "fa" and "fui" also get mixed up with nearby pairs, the highest-scored neighbour is "fa vs fora". Nearby pair

Confusion rank #312,182 of 323,831 scored Spanish pairs, corpus vintage 2026-09-03, not spelling advice.

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

Source: FrequencyWords open word-frequency list