noun
half-sibling (different mother)
Refers specifically to siblings who share the same father but have different mothers. Not used for half-siblings with a different father.
彼には異母兄弟が二人いる。
He has two half-siblings from a different mother.
異父兄弟 refers to half-siblings with a different father, while 異母兄弟 refers to those with a different mother.
Compound of 異 (different) + 母 (mother) + 兄弟 (siblings).