seinvsserWhich spelling fits?

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

Which to use

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

#43,647
“sein” frequency rank
#30
“ser” frequency rank
43677
confusion score

Side-by-Side Comparison

Feature sein ser
Definition ser, estar. existir, aquilo que supõe-se existir

Where the eye mixes sein and ser

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

4 ch
sein
3 ch
ser

Why the eye confuses sein with ser

These two trip readers on the page rather than in the ear: sein is /zaɪ̯n/ while ser is /ˈseɾ/. 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 (verb vs noun), which is usually the fastest check. Our composite confusion score for this pair is 43677, derived from the frequency rank of both members and their visual similarity.

sein is recorded at frequency rank #43,647, classified as averb, pronounced /zaɪ̯n/. ser is at rank #30, tagged as anoun, pronounced /ˈseɾ/.

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 43677, this pair ranks #21,946 of 75,631 scored Portuguese confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of sein vs ser

Shared letters: es. Private to "sein": in. Private to "ser": r.

"sein" · 4 letters · shape CVVC  ·  "ser" · 3 letters · shape CVC

Known mistypes of this pair

  • seinesin · seinn · seni · sien · ssein

Frequently Asked Questions

Is swapping "sein" for "ser" ever safe?
No - they are not even the same part of speech. "sein" is a verb and "ser" a noun, so a sentence built for one is usually ungrammatical with the other.
Frequency check: "sein" vs "ser" - which ranks higher?
"ser" is the more common of the two: it sits at frequency rank #30 in our Portuguese list, against #43,647 for "sein". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

What to do next

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

  • Full dictionary entry for "sein" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "ser" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #21,946 of 75,631 scored Portuguese confusable pairs in this corpus vintage. Corpus statistics
  • "sein" and "ser" also get mixed up with nearby pairs, the highest-scored neighbour is "sein vs slip". 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 #21,946 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