Origin of foster brother
Examples from the Web for foster brother
I was his foster-brother and playfellow, unequal as was our rank.
But he kept off lawyers—and he sought out the only man he could remember—his foster-brother, Harborough.The Borough Treasurer|Joseph Smith Fletcher
Myself have seen and known even a baby envious; it could not speak, yet it turned pale and looked bitterly on its foster-brother.The Confessions of Saint Augustine|Saint Augustine
Now, the Prince had a foster-brother who was a very wicked man.
Do you remember your foster-brother who pulled you out of the water one day?Sylvie: souvenirs du Valois|Grard de Nerval