suvssunTell them apart

Quick tell: su is a adjective, sun is a noun, so they fill different roles in a sentence.

Which to use

“su” is an adjective and “sun” is a noun - they look or sound alike but fill different roles in a sentence.

#20
“su” frequency rank
#8,323
“sun” frequency rank
8343
confusion score

Side-by-Side Comparison

Feature su sun
Definition Adjetivo posesivo de la tercera persona; de él, de ella, de ellos, de ellas. Sol₂.

Where the eye mixes su and sun

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

2 ch
su
3 ch
sun

Visual trap between su and sun

These two trip readers on the page rather than in the ear: su is [su] while sun is /sʌn/. Spoken aloud the problem disappears. In writing it persists, because they differ by 1 extra letter(s) - “su” sits inside “sun”, and the parts of speech differ too (adjective vs noun), which is usually the fastest check. Our composite confusion score for this pair is 8343, derived from the frequency rank of both members and their visual similarity.

su is recorded at frequency rank #20, classified as anadj, pronounced [su]. sun is at rank #8,323, tagged as anoun, pronounced /sʌn/.

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 8343, this pair ranks #305,274 of 323,831 scored Spanish confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of su vs sun

Shared letters: su. Private to "su": -. Private to "sun": n.

"su" · 2 letters · shape CV  ·  "sun" · 3 letters · shape CVC

Frequently Asked Questions

Can "su" and "sun" be used interchangeably?
No - they are not even the same part of speech. "su" is an adjective and "sun" a noun, so a sentence built for one is usually ungrammatical with the other.
In ordinary Spanish text, does "su" or "sun" show up more?
"su" is the more common of the two: it sits at frequency rank #20 in our Spanish list, against #8,323 for "sun". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

Useful next steps

Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.

  • Full dictionary entry for "su" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "sun" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #305,274 of 323,831 scored Spanish confusable pairs in this corpus vintage. Corpus statistics
  • "su" and "sun" also get mixed up with nearby pairs, the highest-scored neighbour is "sous vs sun". Nearby pair

Confusion rank #305,274 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