flapvsflaskWhich spelling fits?

Which to use

“flap” and “flask” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.

#15,170
“flap” frequency rank
#22,379
“flask” frequency rank
37549
confusion score

Side-by-Side Comparison

Feature flap flask
Definition Anything broad and flexible that hangs loose, or that is attached by one side or end and is easily moved. 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 flap and flask

Muted = shared; highlighted = the visual trap. They share 3 letters in sequence.

4 ch
flap
5 ch
flask

Visual trap between flap and flask

A purely visual mix-up. flap (/flæp/) and flask (/ˈflɑːsk/) 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 37549, derived from the frequency rank of both members and their visual similarity.

flap is recorded at frequency rank #15,170, classified as anoun, pronounced /flæp/. 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 37549, this pair ranks #293,622 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of flap vs flask

Shared letters: afl. Private to "flap": p. Private to "flask": ks.

"flap" · 4 letters · shape CCVC  ·  "flask" · 5 letters · shape CCVCC

Known mistypes of this pair

  • flapfalp · fflap · flapp · fllap · flpa · lfap
  • flaskfalsk · fflask · flaks · flaskk · flassk · fllask · flsak · lfask

Frequently Asked Questions

Is swapping "flap" for "flask" ever safe?
No. They are said differently (/flæp/ versus /ˈflɑːsk/) and carry different meanings; reading the sentence aloud is usually enough to catch the wrong one.
Frequency check: "flap" vs "flask" - which ranks higher?
"flap" is the more common of the two: it sits at frequency rank #15,170 in our English list, against #22,379 for "flask". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

Eye-level mix-up between "flap" and "flask" is sorted above. Next: full entries or other pairs that share a letter shape.

  • Full dictionary entry for "flap" 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 #293,622 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "flap" 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

Confusion rank #293,622 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list