Which to use
“fasten” and “flatten” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.
- #29,649
- “fasten” frequency rank
- #29,657
- “flatten” frequency rank
- 59306
- confusion score
Side-by-Side Comparison
| Feature | fasten | flatten |
|---|---|---|
| Definition | To attach or connect in a secure manner. | To make something flat or flatter. |
Where the eye mixes fasten and flatten
Muted = shared; highlighted = the visual trap. They share 5 letters in sequence.
Why the eye confuses fasten with flatten
A purely visual mix-up. fasten (/ˈfɑːsn̩/) and flatten (/ˈflæ.tən/) are said differently, so reading them aloud is the quickest way to catch the wrong one. On the page they stay close: they differ by 1 letter(s) in length. Our composite confusion score for this pair is 59306, derived from the frequency rank of both members and their visual similarity.
fasten is recorded at frequency rank #29,649, classified as averb, pronounced /ˈfɑːsn̩/. flatten is at rank #29,657, tagged as averb, pronounced /ˈflæ.tən/.
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 59306, this pair ranks #107,089 of 530,003 scored English confusable pairs - among the most confusable pairs.
Orthographic DNA of fasten vs flatten
Shared letters: aefnt. Private to "fasten": s. Private to "flatten": l.
"fasten" · 6 letters · shape CVCCVC · "flatten" · 7 letters · shape CCVCCVC
Known mistypes of this pair
Frequently Asked Questions
Is swapping "fasten" for "flatten" ever safe?
Frequency check: "fasten" vs "flatten" - which ranks higher?
What to do next
Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.
- Full dictionary entry for "fasten" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "flatten" - compare definitions side by side with the headword page. Word entry
- This pair ranks #107,089 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "fasten" and "flatten" also get mixed up with nearby pairs, the highest-scored neighbour is "fasten vs fastener". 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 #107,089 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.