a boy brought up with another child of different parents.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use foster brother in a sentence
So he rode home to call Virginia City, to ask for his foster brother-in-law.
The hound followed Bruce, who gradually dispersed his company,66 at last keeping only his foster-brother with him.King Robert the Bruce | A. F. Murison
He then killed his own two pursuers, while his foster-brother despatched the only one remaining.King Robert the Bruce | A. F. Murison
"It doesn't seem like it, Job," said Alice sadly, and looked with distress on the splendid figure of her foster-brother.A Son of Perdition | Fergus Hume
The count drew up a butaca, sat down opposite Valentine, took a cigar from the case his foster brother handed him, and lit it.The Gold-Seekers | Gustave Aimard
Louis was too well acquainted with his foster brother's firm and resolute character to try and combat his will.The Gold-Seekers | Gustave Aimard