Which to use
“ill” is an adjective and “isa” is a noun - they look or sound alike but fill different roles in a sentence.
- #43,059
- “ill” frequency rank
- #17,738
- “isa” frequency rank
- 60797
- confusion score
Side-by-Side Comparison
| Feature | ill | isa |
|---|---|---|
| Definition | Enfermo. | Estilo musical vocal, en ritmo de tres cuartos, típico de las Islas Canarias. |
Where the eye mixes ill and isa
Muted = shared; highlighted = the visual trap. They share 1 letter in sequence.
Why the eye confuses ill with isa
These two trip readers on the page rather than in the ear: ill is /ɪl/ while isa is [ˈisa]. Spoken aloud the problem disappears. In writing it persists, because they share most of their letters but differ in 2 positions, and the parts of speech differ too (adjective vs noun), which is usually the fastest check. Our composite confusion score for this pair is 60797, derived from the frequency rank of both members and their visual similarity.
ill is recorded at frequency rank #43,059, classified as anadj, pronounced /ɪl/. isa is at rank #17,738, tagged as anoun, pronounced [ˈisa].
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 60797, this pair ranks #57,701 of 323,831 scored Spanish confusable pairs - among the most confusable pairs.
Orthographic DNA of ill vs isa
Shared letters: i. Private to "ill": l. Private to "isa": as.
"ill" · 3 letters · shape VCC · "isa" · 3 letters · shape VCV
Frequently Asked Questions
Can "ill" and "isa" be used interchangeably?
Which is more common, "ill" or "isa"?
Useful next steps
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 "isa" - compare definitions side by side with the headword page. Word entry
- This pair ranks #57,701 of 323,831 scored Spanish confusable pairs in this corpus vintage. Corpus statistics
- "ill" and "isa" also get mixed up with nearby pairs, the highest-scored neighbour is "ill vs iza". Nearby pair
Confusion rank #57,701 of 323,831 scored Spanish pairs, corpus vintage 2026-09-03, not spelling advice.