Which to use
“fill” is a verb and “fly” is a noun - they look or sound alike but fill different roles in a sentence.
- #2,297
- “fill” frequency rank
- #1,827
- “fly” frequency rank
- 4124
- confusion score
Side-by-Side Comparison
| Feature | fill | fly |
|---|---|---|
| Definition | To make full | Any insect of the order Diptera; characterized by having two wings (except for some wingless species), also called true flies. |
Where the eye mixes fill and fly
Muted = shared; highlighted = the visual trap. They share 2 letters in sequence.
Visual trap between fill and fly
These two trip readers on the page rather than in the ear: fill is /fɪl/ while fly is /flaɪ/. 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 (verb vs noun), which is usually the fastest check. Our composite confusion score for this pair is 4124, derived from the frequency rank of both members and their visual similarity.
fill is recorded at frequency rank #2,297, classified as averb, pronounced /fɪl/. fly is at rank #1,827, tagged as anoun, pronounced /flaɪ/.
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 4124, this pair ranks #519,913 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.
Orthographic DNA of fill vs fly
Shared letters: fl. Private to "fill": i. Private to "fly": y.
"fill" · 4 letters · shape CVCC · "fly" · 3 letters · shape CCV
Known mistypes of this pair
- fill ← ffill · flil · ifll
Frequently Asked Questions
Do "fill" and "fly" mean the same thing in a sentence?
Which is more common, "fill" or "fly"?
Useful next steps
Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.
- Full dictionary entry for "fill" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "fly" - compare definitions side by side with the headword page. Word entry
- This pair ranks #519,913 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "fill" and "fly" also get mixed up with nearby pairs, the highest-scored neighbour is "fly vs foh". 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 #519,913 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.