Translation guide
In Japanese, there is no single common word for 'half-sibling'. Instead, you specify the shared parent using terms like 異母 (different mother) or 異父 (different father), or describe the relationship with phrases. In everyday conversation, people often just say 兄弟 (siblings) and clarify if needed.
To refer to a half-sibling in a neutral or explanatory way.
Literally 'different-mother siblings'. Used when siblings share the same father but have different mothers. Can refer to any gender combination.
He is my half-sibling (same father, different mother).
Literally 'different-father siblings'. Used when siblings share the same mother but have different fathers.
She is my half-sibling (same mother, different father).
A more colloquial term for half-siblings, literally 'different-belly siblings'. Usually implies same father, different mother. Can sound a bit old-fashioned or blunt.
He is my half-brother (same father, different mother).
Literally 'different-seed siblings'. Implies same mother, different father. Rare and somewhat crude; avoid in polite conversation.
I have a half-sibling (same mother, different father).
To specify a male half-sibling.
Older half-brother (same father, different mother). Use 異母弟 (いぼてい) for younger half-brother.
I have two older half-brothers (same father, different mother).
Older half-brother (same mother, different father). Use 異父弟 (いふてい) for younger.
My younger half-brother (same mother, different father) is still a student.
To specify a female half-sibling.
Older half-sister (same father, different mother). Use 異母妹 (いぼまい) for younger.
My older half-sister (same father, different mother) lives abroad.
Older half-sister (same mother, different father). Use 異父妹 (いふまい) for younger.
I often play with my younger half-sister (same mother, different father).
To mention a half-sibling in casual conversation without specifying the biological relationship.
In daily life, Japanese speakers often don't distinguish half-siblings from full siblings unless necessary. You can simply say 兄 (あに), 弟 (おとうと), 姉 (あね), 妹 (いもうと) as usual.
I have an older brother. Actually, he's my half-brother (same father, different mother).
A descriptive phrase meaning 'siblings with a different father'. Natural in conversation when clarification is needed.
He is my younger brother from a different father.
Descriptive phrase meaning 'siblings with a different mother'.
I have a younger sister from a different mother.
The word 兄弟 can refer to siblings in general, including sisters. If you want to emphasize only sisters, use 姉妹 (しまい). For half-siblings, 異母兄弟 or 異父兄弟 are gender-neutral.
There is no direct equivalent of 'half-sibling' as a single word. Using ハーフシブリング would not be understood. Always specify the shared parent or use descriptive phrases.