English UsageGrammar guide
Plural of Nucleus
The noun “nucleus” has the established plural “nuclei,” and Cambridge also records “nucleuses.” The traditional “nuclei” form is especially familiar in scientific contexts.
Use “nuclei” as the standard traditional plural of “nucleus”; “nucleuses” is also recorded as a plural form.
Key details
Confusion Familycompeting classical and regularized plurals
Rule Familyplural and countability
Termsnucleus, nuclei, nucleuses
Variant ScopeCambridge lists both “nuclei” and “nucleuses”; scientific usage commonly uses “nuclei.”
Further guidance
Core difference
Both forms are plurals of “nucleus,” with “nuclei” the established classical form.
Fast Test
In scientific writing, “nuclei” is usually the expected form; elsewhere, follow the terminology of your field or house style.
Usage Boundary
Keep pronunciation and spelling distinct: “nuclei” is not formed by simply adding -s to “nucleus.”
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- NUCLEUS — Cambridge Dictionary (opens in a new tab)Cambridge University Press · Direct inflection evidence listing nuclei and nucleuses as plurals of nucleus.