IJ vs ill, What's the Difference?

Which to use

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

#46,535
“IJ” frequency rank: #1,946
“ill” frequency rank: 48481
confusion score

Side-by-Side Comparison

Feature	IJ	ill
Definition	A lake (formerly a bay) adjoining the city of Amsterdam, Netherlands.	Evil; wicked (of people).

Where the eye mixes IJ and ill

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

2 ch

3 ch

ill

Why the eye confuses IJ with ill

These two trip readers on the page rather than in the ear: IJ is /eɪ/ while ill is /ɪl/. 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 (name vs adjective), which is usually the fastest check. Our composite confusion score for this pair is 48481, derived from the frequency rank of both members and their visual similarity.

IJ is recorded at frequency rank #46,535, classified as aname, pronounced /eɪ/. ill is at rank #1,946, tagged as anadj, pronounced /ɪl/.

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 48481, this pair ranks #192,699 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of IJ vs ill

Shared letters: i. Private to "IJ": j. Private to "ill": l.

"IJ" · 2 letters · shape VC · "ill" · 3 letters · shape VCC

Frequently Asked Questions

Can "IJ" and "ill" be used interchangeably?

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

Frequency check: "IJ" vs "ill" - which ranks higher?

"ill" is the more common of the two: it sits at frequency rank #1,946 in our English list, against #46,535 for "IJ". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

Useful next steps

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

Full dictionary entry for "IJ" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "ill" - compare definitions side by side with the headword page. Word entry
This pair ranks #192,699 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
"IJ" and "ill" also get mixed up with nearby pairs, the highest-scored neighbour is "IJ vs ith". Nearby pair

Confusion rank #192,699 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.