koivsKosWhat's the difference?

Quick tell: koi is a noun, Kos is a name, so they fill different roles in a sentence.

Which to use

“koi” is a noun and “Kos” is a name - they look or sound alike but fill different roles in a sentence.

#26,483
“koi” frequency rank
#27,534
“Kos” frequency rank
54017
confusion score

Side-by-Side Comparison

Feature koi Kos
Definition Ornamental domesticated varieties of the Amur carp (Cyprinus rubrofuscus), of Japan and eastern Asia with red-gold or white coloring. An island of the Dodecanese, Greece.

Letter map: koi vs Kos

Shared letters muted; letters that set koi and Kos apart highlighted. Shared run: 2.

3 ch
koi
3 ch
Kos

Part-of-speech tell for koi / Kos

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: koi is anoun and Kosaname. On the page they differ by a single letter - i in “koi” becomes s in “Kos”. Our composite confusion score for this pair is 54017, derived from the frequency rank of both members and their visual similarity.

koi is recorded at frequency rank #26,483, classified as anoun, pronounced /kɔɪ/. Kos is at rank #27,534, tagged as aname.

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 54017, this pair ranks #144,397 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of koi vs Kos

Shared letters: ko. Private to "koi": i. Private to "Kos": s.

"koi" · 3 letters · shape CVV  ·  "Kos" · 3 letters · shape CVC

Frequently Asked Questions

Is swapping "koi" for "Kos" ever safe?
No - they are not even the same part of speech. "koi" is a noun and "Kos" a name, so a sentence built for one is usually ungrammatical with the other.
In ordinary English text, does "koi" or "Kos" show up more?
"koi" is the more common of the two: it sits at frequency rank #26,483 in our English list, against #27,534 for "Kos". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Useful next steps

Done with this confusable. These links stay specific to "koi" and "Kos".

  • Full dictionary entry for "koi" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "Kos" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #144,397 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "koi" and "Kos" also get mixed up with nearby pairs, the highest-scored neighbour is "Kop vs Kos". Nearby pair

Confusion rank #144,397 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