ill vs iu, What's the Difference?

Which to use

“ill” is an adjective and “iu” is an abbrev - they look or sound alike but fill different roles in a sentence.

#44,899
“ill” frequency rank: #42,065
“iu” frequency rank: 86964
confusion score

Side-by-Side Comparison

Feature	ill	iu
Definition	doente	código de língua ISO 639-3 para a macrolíngua esquimó/inuktitut

Where the eye mixes ill and iu

Muted = shared; highlighted = the visual trap. They share 1 letter in sequence.

3 ch

ill

2 ch

Look-alike desk: ill vs iu

These two trip readers on the page rather than in the ear: ill is /ɪl/ while iu is /ˈi.u/, /ˈi.ʊ/. Spoken aloud the problem disappears. In writing it persists, because they differ by 1 letter(s) in length, and the parts of speech differ too (adjective vs abbrev), which is usually the fastest check. Our composite confusion score for this pair is 86964, derived from the frequency rank of both members and their visual similarity.

ill is recorded at frequency rank #44,899, classified as anadj, pronounced /ɪl/. iu is at rank #42,065, tagged as anabbrev, pronounced /ˈi.u/, /ˈi.ʊ/.

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 86964, this pair ranks #534 of 75,631 scored Portuguese confusable pairs - among the most confusable pairs.

Orthographic DNA of ill vs iu

Shared letters: i. Private to "ill": l. Private to "iu": u.

"ill" · 3 letters · shape VCC · "iu" · 2 letters · shape VV

Frequently Asked Questions

Is swapping "ill" for "iu" ever safe?

No - they are not even the same part of speech. "ill" is an adjective and "iu" an abbrev, so a sentence built for one is usually ungrammatical with the other.

In ordinary Portuguese text, does "ill" or "iu" show up more?

"iu" is the more common of the two: it sits at frequency rank #42,065 in our Portuguese list, against #44,899 for "ill". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.

Full dictionary entry for "ill" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "iu" - compare definitions side by side with the headword page. Word entry
This pair ranks #534 of 75,631 scored Portuguese confusable pairs in this corpus vintage. Corpus statistics
"ill" and "iu" also get mixed up with nearby pairs, the highest-scored neighbour is "ill vs ino". Nearby pair

Confusion rank #534 of 75,631 scored Portuguese pairs, corpus vintage 2026-09-03, not spelling advice.