Plural of Brother
“Brother” has the regular plural “brothers” and the specialized/register-marked plural “brethren.” Use “brothers” for ordinary literal or general reference; reserve “brethren” for contexts where its older organizational or religious sense is intended.
For ordinary family/reference use, the plural is “brothers.” “Brethren” is another plural form, but it is old-fashioned and especially associated with members of organizations or religious groups.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| male siblings/general plural | brothers | Normal modern plural. |
| members addressed as a religious/organizational group | brethren | Marked old-fashioned/group use. |
| one male sibling/member | brother | Singular. |
Quick tests
Plural-choice test
Are you simply referring to more than one male sibling or ordinary “brother”?
If yes: Use “brothers.”
If no: Use “brethren” only if the older organizational/religious sense is intended.
Caveat: The reviewed Cambridge evidence marks “brethren” old-fashioned and group/religious in use.
Examples
Her two brothers live nearby.
Ordinary family reference uses “brothers.”
The speaker addressed the assembled brethren.
“Brethren” fits a marked group/religious context.
My brother called this morning.
One takes singular “brother.”
Further guidance
Core difference
Use “brothers” as the normal plural; use “brethren” only when the old-fashioned/group/religious meaning fits.
Fast Test
If you literally mean male siblings, “brothers” is the safe default.
Usage Boundary
Do not choose “brethren” merely to make ordinary family reference sound more formal.
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.
- BROTHER Definition & Meaning - Merriam-Webster (opens in a new tab)Merriam-Webster · Merriam-Webster gives brothers and brethren as plurals of brother.
- BRETHREN | English meaning - Cambridge Dictionary (opens in a new tab)Cambridge University Press · Cambridge labels brethren old-fashioned and ties it to members of an organization or religious group, supporting a register/sense boundary.