iOSvsISSTell them apart

Which to use

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

#5,888
“iOS” frequency rank
#16,055
“ISS” frequency rank
21943
confusion score

Side-by-Side Comparison

Feature iOS ISS
Definition A mobile operating system (OS) created and developed by Apple Inc. exclusively for its hardware. Initialism of International Space Station.

Letter map: iOS vs ISS

Shared letters muted; letters that set iOS and ISS apart highlighted. Shared run: 2.

3 ch
iOS
3 ch
ISS

Spelling & dictionary notes on iOS vs ISS

iOS and ISS 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 - o in “iOS” becomes s in “ISS”. Our composite confusion score for this pair is 21943, derived from the frequency rank of both members and their visual similarity.

iOS is recorded at frequency rank #5,888, classified as aname. ISS is at rank #16,055, tagged as aname.

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 21943, this pair ranks #420,223 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of iOS vs ISS

Shared letters: is. Private to "iOS": o. Private to "ISS": -.

"iOS" · 3 letters · shape VVC  ·  "ISS" · 3 letters · shape VCC

Frequently Asked Questions

Is swapping "iOS" for "ISS" ever safe?
No. They differ by a single letter - o in “iOS” becomes s in “ISS”, but the dictionary glosses above give them different meanings, so swapping one for the other changes what the sentence says.
In ordinary English text, does "iOS" or "ISS" show up more?
"iOS" is the more common of the two: it sits at frequency rank #5,888 in our English list, against #16,055 for "ISS". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Useful next steps

Pair "iOS" vs "ISS" is on the table, pick a follow-up below.

  • Full dictionary entry for "iOS" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "ISS" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #420,223 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "iOS" and "ISS" also get mixed up with nearby pairs, the highest-scored neighbour is "ISS vs ith". Nearby pair

Confusion rank #420,223 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