IESvsisiTell them apart

Quick tell: IES is a abbrev, isi is a noun, so they fill different roles in a sentence.

Which to use

“IES” is an abbrev and “isi” is a noun - they look or sound alike but fill different roles in a sentence.

#21,019
“IES” frequency rank
#39,822
“isi” frequency rank
60841
confusion score

Side-by-Side Comparison

Feature IES isi
Definition Instituto de Educación Secundaria (España). El extranjero, tierra o país de donde uno no es.

Where the eye mixes IES and isi

Muted = shared; highlighted = the visual trap. They share 2 letters in sequence. IES (VVC) and isi (VCV) run the same length but a different consonant-vowel pattern - the shape difference is usually the fastest tell.

3 ch
IES
3 ch
isi

Why the eye confuses IES with isi

These two trip readers on the page rather than in the ear: IES is [ˈjes] while isi is /ì.sí/. 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 (abbrev vs noun), which is usually the fastest check. Our composite confusion score for this pair is 60841, derived from the frequency rank of both members and their visual similarity.

IES is recorded at frequency rank #21,019, classified as anabbrev, pronounced [ˈjes]. isi is at rank #39,822, tagged as anoun, pronounced /ì.sí/.

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 60841, this pair ranks #57,515 of 323,831 scored Spanish confusable pairs - among the most confusable pairs.

Orthographic DNA of IES vs isi

Shared letters: is. Private to "IES": e. Private to "isi": -.

"IES" · 3 letters · shape VVC  ·  "isi" · 3 letters · shape VCV

Frequently Asked Questions

Is swapping "IES" for "isi" ever safe?
No - they are not even the same part of speech. "IES" is an abbrev and "isi" a noun, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "IES" or "isi"?
"IES" is the more common of the two: it sits at frequency rank #21,019 in our Spanish list, against #39,822 for "isi". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

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

  • Full dictionary entry for "IES" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "isi" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #57,515 of 323,831 scored Spanish confusable pairs in this corpus vintage. Corpus statistics
  • "IES" and "isi" also get mixed up with nearby pairs, the highest-scored neighbour is "isi vs iza". Nearby pair

Confusion rank #57,515 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