Which to use
“fast” is an adjective and “flask” is a noun - they look or sound alike but fill different roles in a sentence.
- #767
- “fast” frequency rank
- #22,379
- “flask” frequency rank
- 23146
- confusion score
Side-by-Side Comparison
| Feature | fast | flask |
|---|---|---|
| Definition | Firmly or securely fixed in place; stable. | A narrow-necked vessel of metal or glass, used for various purposes; as of sheet metal, to carry gunpowder in; or of wrought iron, to contain quicksilver; or of glass, to heat water in, etc. |
Where the eye mixes fast and flask
Muted = shared; highlighted = the visual trap. They share 3 letters in sequence.
Spelling & Dictionary Insight
These two trip readers on the page rather than in the ear: fast is /fɑːst/ while flask is /ˈflɑːsk/. 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 (adjective vs noun), which is usually the fastest check. Our composite confusion score for this pair is 23146, derived from the frequency rank of both members and their visual similarity.
fast is recorded at frequency rank #767, classified as anadj, pronounced /fɑːst/. flask is at rank #22,379, tagged as anoun, pronounced /ˈflɑːsk/.
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 23146, this pair ranks #411,415 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.
Orthographic DNA of fast vs flask
Shared letters: afs. Private to "fast": t. Private to "flask": kl.
"fast" · 4 letters · shape CVCC · "flask" · 5 letters · shape CCVCC
Known mistypes of this pair
Frequently Asked Questions
Can "fast" and "flask" be used interchangeably?
Which is more common, "fast" or "flask"?
What to do next
You've compared "fast" and "flask". Here's where to go from here.
- Full dictionary entry for "fast" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "flask" - compare definitions side by side with the headword page. Word entry
- This pair ranks #411,415 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "fast" and "flask" also get mixed up with nearby pairs, the highest-scored neighbour is "flail vs flask". 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
PlainSpell is a reference corpus, not spelling advice. Verify unusual forms in context.