Which to use
“cog” and “cos” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.
- #28,496
- “cog” frequency rank
- #6,553
- “cos” frequency rank
- 35049
- confusion score
Side-by-Side Comparison
| Feature | cog | cos |
|---|---|---|
| Definition | A tooth on a gear. | Synonym of romaine lettuce, a long-leaved variety of lettuce. |
Where the eye mixes cog and cos
Muted = shared; highlighted = the visual trap. They share 2 letters in sequence.
Visual trap between cog and cos
A purely visual mix-up. cog (/kɒɡ/) and cos (/kɑs/) 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 a single letter - g in “cog” becomes s in “cos”. Our composite confusion score for this pair is 35049, derived from the frequency rank of both members and their visual similarity.
cog is recorded at frequency rank #28,496, classified as anoun, pronounced /kɒɡ/. cos is at rank #6,553, tagged as anoun, pronounced /kɑs/.
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 35049, this pair ranks #315,350 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of cog vs cos
Shared letters: co. Private to "cog": g. Private to "cos": s.
"cog" · 3 letters · shape CVC · "cos" · 3 letters · shape CVC
Frequently Asked Questions
Is swapping "cog" for "cos" ever safe?
Frequency check: "cog" vs "cos" - which ranks higher?
Useful next steps
Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.
- Full dictionary entry for "cog" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "cos" - compare definitions side by side with the headword page. Word entry
- This pair ranks #315,350 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "cog" and "cos" also get mixed up with nearby pairs, the highest-scored neighbour is "CGT vs cog". Nearby pair
Confusion rank #315,350 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.