n. pl. broth·ers
1. A male having the same parents as another or one parent in common with another.
2. pl. also breth·ren (brĕthrən) One who shares a common ancestry, allegiance, character, or purpose with another or others, especially:
a. A kinsman.
b. A fellow man.
c. A fellow member, as of a fraternity, trade union, or panel of judges on a court.
d. A close male friend; a comrade.
e. A fellow African-American man or boy.
3. pl. also brethren Something, such as a corporation or institution, that is regarded as a member of a class: "A station that ... relies on corporate contributions or advertising to survive runs the risk of becoming virtually indistinguishable from its commercial brethren" (W. John Moore).
a. Abbr. Br. or Bro. A lay member of a religious order of men.
b. pl. also brethren A fellow member of the Christian church.
[Middle English, from Old English brōthor; see bhrāter- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.