Bob and Sharon were married. Timmy is Sharon's brother. Timmy is Bob's brother from another mother.
By Nanny
Brother From Another Mother
A term used to describe a good friend that you have known almost your whole life. The word "brother" is used because the friend is extremely close to you to the point that he is almost like your brother--but from a different mother. And that rhymes. And you know that rhymes. Admit it!
Term commonly used by one Christian man to another. This makes sense since all Christians are "brothers" (belonging to the body of Christ) but most have different mothers.
When your dad leaves your mam and fucks someone else and your mam finds out so your stepbrother has to come over every once a week
Stepbrother: Oh I love you brother
Other stepbrother: we ain't brothers you stupid fucking asshole of a stepbrother, you are my brother from another mother!
By Inesita
Brother From Another Mother
A brother that is only related to you through your father, as in he is your half brother, there fore he is your brother but from another mother.
John and I are brothers, but since he is the son of my step-mom he is my brother from another mother