clouvsCO2Which spelling fits?

Which to use

“clou” and “CO2” are a confusable German pair: similar on the page, but distinct in meaning, check the gloss before you choose.

#39,272
“clou” frequency rank
#4,186
“CO2” frequency rank
43458
confusion score

Side-by-Side Comparison

Feature clou CO2
Definition Nagel chemische Summenformel von Kohlendioxid

Where the eye mixes clou and CO2

Muted = shared; highlighted = the visual trap. They share 2 letters in sequence.

4 ch
clou
3 ch
CO2

Why the eye confuses clou with CO2

A purely visual mix-up. clou ([klu]) and CO2 ([ˌt͡seːoˈt͡svaɪ̯]) 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 43458, derived from the frequency rank of both members and their visual similarity.

clou is recorded at frequency rank #39,272, classified as anoun, pronounced [klu]. CO2 is at rank #4,186, tagged as anoun, pronounced [ˌt͡seːoˈt͡svaɪ̯].

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 43458, this pair ranks #1,417,470 of 2,006,359 scored German confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of clou vs CO2

Shared letters: co. Private to "clou": lu. Private to "CO2": -.

"clou" · 4 letters · shape CCVV  ·  "CO2" · 2 letters · shape CV

Known mistypes of this pair

  • cloucclou · cllou · cluo · colu · lcou

Frequently Asked Questions

Do "clou" and "CO2" mean the same thing in a sentence?
No. They are said differently ([klu] versus [ˌt͡seːoˈt͡svaɪ̯]) and carry different meanings; reading the sentence aloud is usually enough to catch the wrong one.
Which is more common, "clou" or "CO2"?
"CO2" is the more common of the two: it sits at frequency rank #4,186 in our German list, against #39,272 for "clou". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Useful next steps

Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.

  • Full dictionary entry for "clou" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "CO2" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #1,417,470 of 2,006,359 scored German confusable pairs in this corpus vintage. Corpus statistics
  • "clou" and "CO2" also get mixed up with nearby pairs, the highest-scored neighbour is "clock vs clou". 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 #1,417,470 of 2,006,359 scored German pairs, corpus vintage 2026-09-03, not spelling advice.

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

Source: FrequencyWords open word-frequency list