nucleivsnucleusTell them apart

Which to use

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

#22,751
“nuclei” frequency rank
#13,203
“nucleus” frequency rank
35954
confusion score

Side-by-Side Comparison

Feature nuclei nucleus
Definition plural of nucleus The core, central part of something, around which other elements are assembled.

Where the eye mixes nuclei and nucleus

Muted = shared; highlighted = the visual trap. They share 5 letters in sequence. nuclei runs 6 letters (CVCCVV) against nucleus's 7 (CVCCVVC) - the length gap alone is often enough to separate them once you know to check it.

6 ch
nuclei
7 ch
nucleus

Visual trap between nuclei and nucleus

A purely visual mix-up. nuclei (/ˈnjuː.kli.aɪ/) and nucleus (/ˈnjuː.kli.əs/) 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 35954, derived from the frequency rank of both members and their visual similarity.

nuclei is recorded at frequency rank #22,751, classified as anoun, pronounced /ˈnjuː.kli.aɪ/. nucleus is at rank #13,203, tagged as anoun, pronounced /ˈnjuː.kli.əs/.

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 35954, this pair ranks #307,472 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of nuclei vs nucleus

Shared letters: celnu. Private to "nuclei": i. Private to "nucleus": s.

"nuclei" · 6 letters · shape CVCCVV  ·  "nucleus" · 7 letters · shape CVCCVVC

Known mistypes of this pair

  • nuclei ← nculei · nnuclei · nucclei · nuceli · nuclie · nucllei · nulcei · unclei
  • nucleus ← nculeus · nnucleus · nuccleus · nucelus · nuclesu · nucleuss · nuclleus · nuclues

Frequently Asked Questions

Do "nuclei" and "nucleus" mean the same thing in a sentence?
No. They are said differently (/ˈnjuː.kli.aɪ/ versus /ˈnjuː.kli.əs/) and carry different meanings; reading the sentence aloud is usually enough to catch the wrong one.
Frequency check: "nuclei" vs "nucleus" - which ranks higher?
"nucleus" is the more common of the two: it sits at frequency rank #13,203 in our English list, against #22,751 for "nuclei". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

What to do next

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

  • Full dictionary entry for "nuclei" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "nucleus" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #307,472 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "nuclei" and "nucleus" also get mixed up with nearby pairs, the highest-scored neighbour is "nuclei vs nucleic". 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 #307,472 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