sei vs seu, What's the Difference?

Which to use

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

#48,072
“sei” frequency rank: #35,751
“seu” frequency rank: 83823
confusion score

Side-by-Side Comparison

Feature	sei	seu
Definition	Seis.	Su.

Where the eye mixes sei and seu

Muted = shared; highlighted = the visual trap. They share 2 letters in sequence. sei and seu follow the identical consonant-vowel pattern (CVV). Same shape at a glance is often the real trap, independent of shared letters.

3 ch

sei

3 ch

seu

Look-alike desk: sei vs seu

These two trip readers on the page rather than in the ear: sei is /s̺ej/ while seu is [ˈsew]. Spoken aloud the problem disappears. In writing it persists, because they differ by a single letter - i in “sei” becomes u in “seu”, and the parts of speech differ too (num vs adjective), which is usually the fastest check. Our composite confusion score for this pair is 83823, derived from the frequency rank of both members and their visual similarity.

sei is recorded at frequency rank #48,072, classified as anum, pronounced /s̺ej/. seu is at rank #35,751, tagged as anadj, pronounced [ˈsew].

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 83823, this pair ranks #7,688 of 323,831 scored Spanish confusable pairs - among the most confusable pairs.

Orthographic DNA of sei vs seu

Shared letters: es. Private to "sei": i. Private to "seu": u.

"sei" · 3 letters · shape CVV · "seu" · 3 letters · shape CVV

Frequently Asked Questions

Do "sei" and "seu" mean the same thing in a sentence?

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

Which is more common, "sei" or "seu"?

"seu" is the more common of the two: it sits at frequency rank #35,751 in our Spanish list, against #48,072 for "sei". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

What to do next

Eye-level mix-up between "sei" and "seu" is sorted above. Next: full entries or other pairs that share a letter shape.

Full dictionary entry for "sei" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "seu" - compare definitions side by side with the headword page. Word entry
This pair ranks #7,688 of 323,831 scored Spanish confusable pairs in this corpus vintage. Corpus statistics
"sei" and "seu" also get mixed up with nearby pairs, the highest-scored neighbour is "sei vs stem". Nearby pair

Confusion rank #7,688 of 323,831 scored Spanish pairs, corpus vintage 2026-09-03, not spelling advice.