ocovsonceTell them apart

Quick tell: oco is a adjective, once is a num, so they fill different roles in a sentence.

Which to use

“oco” is an adjective and “once” is a num - they look or sound alike but fill different roles in a sentence.

#27,951
“oco” frequency rank
#12,301
“once” frequency rank
40252
confusion score

Side-by-Side Comparison

Feature oco once
Definition que não tem miolo onze

Where the eye mixes oco and once

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

3 ch
oco
4 ch
once

Visual trap between oco and once

These two trip readers on the page rather than in the ear: oco is /ˈo.ku/ while once is /ˈɔnθe/. 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 (adjective vs num), which is usually the fastest check. Our composite confusion score for this pair is 40252, derived from the frequency rank of both members and their visual similarity.

oco is recorded at frequency rank #27,951, classified as anadj, pronounced /ˈo.ku/. once is at rank #12,301, tagged as anum, pronounced /ˈɔnθe/.

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 40252, this pair ranks #25,903 of 75,631 scored Portuguese confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of oco vs once

Shared letters: co. Private to "oco": -. Private to "once": en.

"oco" · 3 letters · shape VCV  ·  "once" · 4 letters · shape VCCV

Known mistypes of this pair

  • oncenoce · oncce · onec · onnce

Frequently Asked Questions

Can "oco" and "once" be used interchangeably?
No - they are not even the same part of speech. "oco" is an adjective and "once" a num, so a sentence built for one is usually ungrammatical with the other.
In ordinary Portuguese text, does "oco" or "once" show up more?
"once" is the more common of the two: it sits at frequency rank #12,301 in our Portuguese list, against #27,951 for "oco". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Useful next steps

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

  • Full dictionary entry for "oco" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "once" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #25,903 of 75,631 scored Portuguese confusable pairs in this corpus vintage. Corpus statistics
  • "oco" and "once" also get mixed up with nearby pairs, the highest-scored neighbour is "oco vs oni". Nearby pair
  • Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes

Confusion rank #25,903 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