cosvscuspTell them apart

Which to use

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

#6,553
“cos” frequency rank
#27,112
“cusp” frequency rank
33665
confusion score

Side-by-Side Comparison

Feature cos cusp
Definition Synonym of romaine lettuce, a long-leaved variety of lettuce. A sharp point or pointed end.

Where the eye mixes cos and cusp

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

3 ch
cos
4 ch
cusp

Visual trap between cos and cusp

A purely visual mix-up. cos (/kɑs/) and cusp (/kʌsp/) 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 33665, derived from the frequency rank of both members and their visual similarity.

cos is recorded at frequency rank #6,553, classified as anoun, pronounced /kɑs/. cusp is at rank #27,112, tagged as anoun, pronounced /kʌsp/.

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 33665, this pair ranks #327,439 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of cos vs cusp

Shared letters: cs. Private to "cos": o. Private to "cusp": pu.

"cos" · 3 letters · shape CVC  ·  "cusp" · 4 letters · shape CVCC

Known mistypes of this pair

  • cuspccusp · csup · cuspp · cussp · ucsp

Frequently Asked Questions

Is swapping "cos" for "cusp" ever safe?
No. They are said differently (/kɑs/ versus /kʌsp/) and carry different meanings; reading the sentence aloud is usually enough to catch the wrong one.
In ordinary English text, does "cos" or "cusp" show up more?
"cos" is the more common of the two: it sits at frequency rank #6,553 in our English list, against #27,112 for "cusp". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

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

  • Full dictionary entry for "cos" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "cusp" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #327,439 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "cos" and "cusp" also get mixed up with nearby pairs, the highest-scored neighbour is "cuny vs cusp". 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 #327,439 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