rexvsrioWhich spelling fits?

Which to use

“rex” and “rio” are a confusable Portuguese pair: similar on the page, but distinct in meaning, check the gloss before you choose.

#12,766
“rex” frequency rank
#173
“rio” frequency rank
12939
confusion score

Side-by-Side Comparison

Feature rex rio
Definition cachorro curso por onde passa água doce continuamente (ou durante épocas específicas do ano)

Letter map: rex vs rio

Shared letters muted; letters that set rex and rio apart highlighted. Shared run: 1.

3 ch
rex
3 ch
rio

Pair insight - rex / rio

rex and rio are indexed as a confusable Portuguese pair. We have no recorded pronunciation or part of speech for both members, so the spelling overlap is what we can show you: they share most of their letters but differ in 2 positions. Our composite confusion score for this pair is 12939, derived from the frequency rank of both members and their visual similarity.

rex is recorded at frequency rank #12,766, classified as anoun. rio is at rank #173, tagged as anoun, pronounced /ʁi.u/ [ʁiu̯].

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 12939, this pair ranks #59,522 of 75,631 scored Portuguese confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of rex vs rio

Shared letters: r. Private to "rex": ex. Private to "rio": io.

"rex" · 3 letters · shape CVC  ·  "rio" · 3 letters · shape CVV

Frequently Asked Questions

Can "rex" and "rio" be used interchangeably?
No. They share most of their letters but differ in 2 positions, but the dictionary glosses above give them different meanings, so swapping one for the other changes what the sentence says.
Frequency check: "rex" vs "rio" - which ranks higher?
"rio" is the more common of the two: it sits at frequency rank #173 in our Portuguese list, against #12,766 for "rex". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

What to do next

You've compared "rex" and "rio". Here's where to go from here.

  • Full dictionary entry for "rex" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "rio" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #59,522 of 75,631 scored Portuguese confusable pairs in this corpus vintage. Corpus statistics
  • "rex" and "rio" also get mixed up with nearby pairs, the highest-scored neighbour is "revi vs rex". Nearby pair

Confusion rank #59,522 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