Which to use
“fast” is an adverb and “flat” is an adjective - they look or sound alike but fill different roles in a sentence.
- #243
- “fast” frequency rank
- #12,913
- “flat” frequency rank
- 13156
- confusion score
Side-by-Side Comparison
| Feature | fast | flat |
|---|---|---|
| Definition | nicht ganz | flach |
Where the eye mixes fast and flat
Muted = shared; highlighted = the visual trap. They share 3 letters in sequence. fast (CVCC) and flat (CCVC) run the same length but a different consonant-vowel pattern - the shape difference is usually the fastest tell.
Visual trap between fast and flat
These two trip readers on the page rather than in the ear: fast is [fast] while flat is [flæt]. Spoken aloud the problem disappears. In writing it persists, because they share most of their letters but differ in 2 positions, and the parts of speech differ too (adverb vs adjective), which is usually the fastest check. Our composite confusion score for this pair is 13156, derived from the frequency rank of both members and their visual similarity.
fast is recorded at frequency rank #243, classified as anadv, pronounced [fast]. flat is at rank #12,913, tagged as anadj, pronounced [flæt].
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 13156, this pair ranks #1,959,766 of 2,006,359 scored German confusable pairs - a relatively easy-to-tell-apart pair.
Orthographic DNA of fast vs flat
Shared letters: aft. Private to "fast": s. Private to "flat": l.
"fast" · 4 letters · shape CVCC · "flat" · 4 letters · shape CCVC
Known mistypes of this pair
Frequently Asked Questions
Is swapping "fast" for "flat" ever safe?
In ordinary German text, does "fast" or "flat" show up more?
Useful next steps
Eye-level mix-up between "fast" and "flat" is sorted above. Next: full entries or other pairs that share a letter shape.
- Full dictionary entry for "fast" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "flat" - compare definitions side by side with the headword page. Word entry
- This pair ranks #1,959,766 of 2,006,359 scored German confusable pairs in this corpus vintage. Corpus statistics
- "fast" and "flat" also get mixed up with nearby pairs, the highest-scored neighbour is "fist vs flat". 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 #1,959,766 of 2,006,359 scored German pairs, corpus vintage 2026-09-03, not spelling advice.