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
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| one nucleus | nucleus | Use the singular form. |
| standard traditional plural | nuclei | Use this as the usual traditional plural. |
| recorded regularized plural | nucleuses | Also recorded; follow field or house style. |
Quick tests
Meaning / construction test
Do you need the plural of “nucleus”?
If yes: “Nuclei” is the standard traditional choice; “nucleuses” is also recorded.
If no: Use singular “nucleus” for one.
Caveat: The two plural forms are not presented as equally preferred in every field: “nuclei” is the standard traditional form, while “nucleuses” is also recorded.
Examples
The diagram marks one nucleus.
One takes the singular “nucleus.”
The diagram marks three nuclei.
“Nuclei” is the standard traditional plural.
The general-audience draft uses nucleuses consistently.
“Nucleuses” is also a recorded plural form.
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.