peivsproWhat's the difference?

Quick tell: pei is a noun, pro is a preposition, so they fill different roles in a sentence.

Which to use

“pei” is a noun and “pro” is a preposition - they look or sound alike but fill different roles in a sentence.

#45,496
“pei” frequency rank
#1,421
“pro” frequency rank
46917
confusion score

Side-by-Side Comparison

Feature pei pro
Definition Decimoséptima letra del alfabeto hebreo Úsase para indicar el beneficiario de una acción o iniciativa.

Where the eye mixes pei and pro

Muted = shared; highlighted = the visual trap. They share 1 letter in sequence.

3 ch
pei
3 ch
pro

Why the eye confuses pei with pro

These two trip readers on the page rather than in the ear: pei is [ˈpej] while pro is [ˈpɾo]. Spoken aloud the problem disappears. In writing it persists, because they share most of their letters but differ in 2 positions, and the parts of speech differ too (noun vs preposition), which is usually the fastest check. Our composite confusion score for this pair is 46917, derived from the frequency rank of both members and their visual similarity.

pei is recorded at frequency rank #45,496, classified as anoun, pronounced [ˈpej]. pro is at rank #1,421, tagged as aprep, pronounced [ˈpɾo].

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 46917, this pair ranks #123,014 of 323,831 scored Spanish confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of pei vs pro

Shared letters: p. Private to "pei": ei. Private to "pro": or.

"pei" · 3 letters · shape CVV  ·  "pro" · 3 letters · shape CCV

Frequently Asked Questions

Do "pei" and "pro" mean the same thing in a sentence?
No - they are not even the same part of speech. "pei" is a noun and "pro" a preposition, so a sentence built for one is usually ungrammatical with the other.
In ordinary Spanish text, does "pei" or "pro" show up more?
"pro" is the more common of the two: it sits at frequency rank #1,421 in our Spanish list, against #45,496 for "pei". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

After this comparison

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

  • Full dictionary entry for "pei" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "pro" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #123,014 of 323,831 scored Spanish confusable pairs in this corpus vintage. Corpus statistics
  • "pei" and "pro" also get mixed up with nearby pairs, the highest-scored neighbour is "pei vs prey". Nearby pair

Confusion rank #123,014 of 323,831 scored Spanish pairs, corpus vintage 2026-09-03, not spelling advice.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list