ills vs iOS, What's the Difference?

Which to use

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

#28,587
“ills” frequency rank: #5,888
“iOS” frequency rank: 34475
confusion score

Side-by-Side Comparison

Feature	ills	iOS
Definition	plural of ill	A mobile operating system (OS) created and developed by Apple Inc. exclusively for its hardware.

Letter map: ills vs iOS

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

4 ch

ills

3 ch

iOS

Grammar separator: ills vs iOS

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: ills is anoun and iOSaname. On the page they differ by 1 letter(s) in length. Our composite confusion score for this pair is 34475, derived from the frequency rank of both members and their visual similarity.

ills is recorded at frequency rank #28,587, classified as anoun, pronounced /ɪlz/. iOS is at rank #5,888, 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 34475, this pair ranks #320,462 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of ills vs iOS

Shared letters: is. Private to "ills": l. Private to "iOS": o.

"ills" · 4 letters · shape VCCC · "iOS" · 3 letters · shape VVC

Known mistypes of this pair

ills ← illss · ilsl · lils

Frequently Asked Questions

Is swapping "ills" for "iOS" ever safe?

No - they are not even the same part of speech. "ills" is a noun and "iOS" a name, so a sentence built for one is usually ungrammatical with the other.

In ordinary English text, does "ills" or "iOS" show up more?

"iOS" is the more common of the two: it sits at frequency rank #5,888 in our English list, against #28,587 for "ills". 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 "ills" and "iOS".

Full dictionary entry for "ills" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "iOS" - compare definitions side by side with the headword page. Word entry
This pair ranks #320,462 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
"ills" and "iOS" also get mixed up with nearby pairs, the highest-scored neighbour is "Ilan vs ills". Nearby pair
Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes

Confusion rank #320,462 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.