That is all of our kindred that could be gathered in haste; but the brethren Elladan and Elrohir have ridden with us, desiring to go to the war.
And have you marked the brethren Elladan and Elrohir?
And last of all Aragorn greeted Eomer of Rohan, and they embraced, and Aragorn said: ’Between us there can be no word of giving or taking, nor of reward; for we are brethren.
Aragorn and his knights, and the people of Lorien and of Rivendell, made ready to ride; but Faramir and Imrahil remained at Edoras; and Arwen Evenstar remained also, and she said farewell to her brethren.
There are no more uses of "brethren" in the book.
Show samples from other sources
The problem with the Fannie Mae and its GSE brethren is...
The world is my country, all mankind are my brethren, and to do good is my religion.