STI vs STS, What's the Difference?

Which to use

“STI” and “STS” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.

#26,266
“STI” frequency rank: #20,790
“STS” frequency rank: 47056
confusion score

Side-by-Side Comparison

Feature	STI	STS
Definition	Initialism of sexually transmitted infection (also S.T.I.).	Initialism of science and technology studies.

Letter map: STI vs STS

Shared letters muted; letters that set STI and STS apart highlighted. Shared run: 2.

3 ch

STI

3 ch

STS

Corpus notes: STI and STS

STI and STS are indexed as a confusable English pair. We have no recorded pronunciation or part of speech for both members, so the spelling overlap is what we can show you: they differ by a single letter - i in “STI” becomes s in “STS”. Our composite confusion score for this pair is 47056, derived from the frequency rank of both members and their visual similarity.

STI is recorded at frequency rank #26,266, classified as anoun. STS is at rank #20,790, tagged as anoun.

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 47056, this pair ranks #205,965 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of STI vs STS

Shared letters: st. Private to "STI": i. Private to "STS": -.

"STI" · 3 letters · shape CCV · "STS" · 3 letters · shape CCC

Frequently Asked Questions

Can "STI" and "STS" be used interchangeably?

No. They differ by a single letter - i in “STI” becomes s in “STS”, but the dictionary glosses above give them different meanings, so swapping one for the other changes what the sentence says.

Frequency check: "STI" vs "STS" - which ranks higher?

"STS" is the more common of the two: it sits at frequency rank #20,790 in our English list, against #26,266 for "STI". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

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

Full dictionary entry for "STI" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "STS" - compare definitions side by side with the headword page. Word entry
This pair ranks #205,965 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
"STI" and "STS" also get mixed up with nearby pairs, the highest-scored neighbour is "Sif vs STI". Nearby pair

Confusion rank #205,965 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.