Which to use
“infill” is a verb and “infirm” is an adjective - they look or sound alike but fill different roles in a sentence.
- #48,290
- “infill” frequency rank
- #46,546
- “infirm” frequency rank
- 94836
- confusion score
Side-by-Side Comparison
| Feature | infill | infirm |
|---|---|---|
| Definition | To fill in a space, hole or gap. | Weak or ill, not in good health. |
Letter map: infill vs infirm
Shared letters muted; letters that set infill and infirm apart highlighted. Shared run: 4. infill and infirm follow the identical consonant-vowel pattern (VCCVCC). Same shape at a glance is often the real trap, independent of shared letters.
Role in the sentence - infill and infirm
Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: infill is averb and infirmanadjective. On the page they share most of their letters but differ in 2 positions. Our composite confusion score for this pair is 94836, derived from the frequency rank of both members and their visual similarity.
infill is recorded at frequency rank #48,290, classified as averb. infirm is at rank #46,546, tagged as anadj, pronounced /ɪnˈfɜːm/.
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 94836, this pair ranks #1,215 of 530,003 scored English confusable pairs - among the most confusable pairs.
Orthographic DNA of infill vs infirm
Shared letters: fin. Private to "infill": l. Private to "infirm": mr.
"infill" · 6 letters · shape VCCVCC · "infirm" · 6 letters · shape VCCVCC
Known mistypes of this pair
Frequently Asked Questions
Is swapping "infill" for "infirm" ever safe?
In ordinary English text, does "infill" or "infirm" show up more?
Useful next steps
Done with this confusable. These links stay specific to "infill" and "infirm".
- Full dictionary entry for "infill" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "infirm" - compare definitions side by side with the headword page. Word entry
- This pair ranks #1,215 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "infill" and "infirm" also get mixed up with nearby pairs, the highest-scored neighbour is "infidel vs infill". 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 #1,215 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.