Which to use
“fill” is a verb and “foul” is an adjective - they look or sound alike but fill different roles in a sentence.
- #2,297
- “fill” frequency rank
- #6,574
- “foul” frequency rank
- 8871
- confusion score
Side-by-Side Comparison
| Feature | fill | foul |
|---|---|---|
| Definition | To make full | Covered with, or containing unclean matter; dirty. |
Where the spellings diverge
Shared letters are muted; the letters that actually set fill and foul apart are highlighted. They share 2 letters in sequence, which is exactly why the eye skips the difference.
Spelling & Dictionary Insight
fill and foul form a confusable pair in the English index, two distinct headwords that are easily confused because they look alike, sound alike, or both. They share most of their letters but differ in 2 positions - close enough that the eye skips over the difference, far enough that meaning fully diverges. Our composite confusion score for this pair is 8871, 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/. foul is at rank #6,574, tagged as anadj, pronounced /faʊl/.
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 8871, this pair ranks #500,275 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.
Frequency comparison
Frequently Asked Questions
Can "fill" and "foul" be used interchangeably?
Remembering fill vs foul
The fastest way to pick the right one every time.
- Check the role first: if you need a verb, it's “fill”; for an adjective, it's “foul”.
- See each word in full, definition, IPA, etymology and its other confusables. Full “fill” entry
- Browse more pairs most likely to be confused. Most confusable