ills vs ISS, What's the Difference?

Which to use

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

#28,587
“ills” frequency rank: #16,055
“ISS” frequency rank: 44642
confusion score

Side-by-Side Comparison

Feature	ills	ISS
Definition	plural of ill	Initialism of International Space Station.

Letter map: ills vs ISS

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

4 ch

ills

3 ch

ISS

Grammar separator: ills vs ISS

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: ills is anoun and ISSaname. On the page they differ by 1 letter(s) in length. Our composite confusion score for this pair is 44642, 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/. 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 44642, this pair ranks #228,633 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of ills vs ISS

Shared letters: is. Private to "ills": l. Private to "ISS": -.

"ills" · 4 letters · shape VCCC · "ISS" · 3 letters · shape VCC

Known mistypes of this pair

ills ← illss · ilsl · lils

Frequently Asked Questions

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

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

Which is more common, "ills" or "ISS"?

"ISS" is the more common of the two: it sits at frequency rank #16,055 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.

What to do next

You've compared "ills" and "ISS". Here's where to go from here.

Full dictionary entry for "ills" 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 #228,633 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
"ills" and "ISS" 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 #228,633 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.