ills vs ILS, What's the Difference?

Which to use

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

#28,587
“ills” frequency rank: #39,360
“ILS” frequency rank: 67947
confusion score

Side-by-Side Comparison

Feature	ills	ILS
Definition	plural of ill	Initialism of instrument landing system.

Letter map: ills vs ILS

Shared letters muted; letters that set ills and ILS apart highlighted. Shared run: 3.

4 ch

ills

3 ch

ILS

Spelling & dictionary notes on ills vs ILS

ills and ILS 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 1 letter(s) in length. Our composite confusion score for this pair is 67947, 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/. ILS is at rank #39,360, 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 67947, this pair ranks #61,083 of 530,003 scored English confusable pairs - among the most confusable pairs.

Orthographic DNA of ills vs ILS

Shared letters: ils. Private to "ills": -. Private to "ILS": -.

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

Known mistypes of this pair

ills ← illss · ilsl · lils

Frequently Asked Questions

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

No. They differ by 1 letter(s) in length, but the dictionary glosses above give them different meanings, so swapping one for the other changes what the sentence says.

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

"ills" is the more common of the two: it sits at frequency rank #28,587 in our English list, against #39,360 for "ILS". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

Pair "ills" vs "ILS" is on the table, pick a follow-up below.

Full dictionary entry for "ills" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "ILS" - compare definitions side by side with the headword page. Word entry
This pair ranks #61,083 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
"ills" and "ILS" also get mixed up with nearby pairs, the highest-scored neighbour is "Ilan vs ILS". 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 #61,083 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.