on vs os, What's the Difference?

Which to use

“on” is an adjective and “os” is an article - they look or sound alike but fill different roles in a sentence.

#675
“on” frequency rank: #19
“os” frequency rank: 694
confusion score

Side-by-Side Comparison

Feature	on	os
Definition	ligado, ativo (na internet)	usado para apontar um nome definido, único

Letter map: on vs os

Shared letters muted; letters that set on and os apart highlighted. Shared run: 1.

2 ch

Grammar separator: on vs os

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: on is anadjective and osanarticle. On the page they differ by a single letter - n in “on” becomes s in “os”. Our composite confusion score for this pair is 694, derived from the frequency rank of both members and their visual similarity.

on is recorded at frequency rank #675, classified as anadj. os is at rank #19, tagged as anarticle, pronounced /uʃ/, /us/ (menos frequente); enfático: /oʃ/, /os/ (menos frequente).

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 694, this pair ranks #74,960 of 75,631 scored Portuguese confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of on vs os

Shared letters: o. Private to "on": n. Private to "os": s.

"on" · 2 letters · shape VC · "os" · 2 letters · shape VC

Frequently Asked Questions

Can "on" and "os" be used interchangeably?

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

Frequency check: "on" vs "os" - which ranks higher?

"os" is the more common of the two: it sits at frequency rank #19 in our Portuguese list, against #675 for "on". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

Useful next steps

You've compared "on" and "os". Here's where to go from here.

Full dictionary entry for "on" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "os" - compare definitions side by side with the headword page. Word entry
This pair ranks #74,960 of 75,631 scored Portuguese confusable pairs in this corpus vintage. Corpus statistics
"on" and "os" also get mixed up with nearby pairs, the highest-scored neighbour is "on vs oni". Nearby pair

Confusion rank #74,960 of 75,631 scored Portuguese pairs, corpus vintage 2026-09-03, not spelling advice.