STIvssunTell them apart

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

Which to use

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

#26,266
“STI” frequency rank
#1,154
“sun” frequency rank
27420
confusion score

Side-by-Side Comparison

Feature STI sun
Definition Initialism of sexually transmitted infection (also S.T.I.). The star that is closest to the Earth.

Letter map: STI vs sun

Shared letters muted; letters that set STI and sun apart highlighted. Shared run: 1.

3 ch
STI
3 ch
sun

Part-of-speech tell for STI / sun

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: STI is anoun and sunaname. On the page they share most of their letters but differ in 2 positions. Our composite confusion score for this pair is 27420, derived from the frequency rank of both members and their visual similarity.

STI is recorded at frequency rank #26,266, classified as anoun. sun is at rank #1,154, tagged as aname, 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 27420, this pair ranks #379,056 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of STI vs sun

Shared letters: s. Private to "STI": it. Private to "sun": nu.

"STI" · 3 letters · shape CCV  ·  "sun" · 3 letters · shape CVC

Frequently Asked Questions

Do "STI" and "sun" mean the same thing in a sentence?
No - they are not even the same part of speech. "STI" is a noun and "sun" a name, so a sentence built for one is usually ungrammatical with the other.
In ordinary English text, does "STI" or "sun" show up more?
"sun" is the more common of the two: it sits at frequency rank #1,154 in our English list, against #26,266 for "STI". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

What to do next

Done with this confusable. These links stay specific to "STI" and "sun".

  • Full dictionary entry for "STI" 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 #379,056 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "STI" and "sun" also get mixed up with nearby pairs, the highest-scored neighbour is "Sif vs STI". Nearby pair

Confusion rank #379,056 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.

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

Source: FrequencyWords open word-frequency list