A half-brother is a boy or man who shares only one parent with you. You may have the same mother and different fathers, or the same father and different mothers.

A half-brotherhalf-brother（同父異母或同母異父的兄弟） is a boy or man是一個男孩或男人 who shares only one parent with you跟你只有一位共同的父母。You may have the same mother and different fathers你們可能媽媽一樣、爸爸不一樣 or或者 the same father and different mothers爸爸一樣、媽媽不一樣。

A full brother shares both. Though actually, many families never say “half-” at home.

A full brother親兄弟 shares both兩邊的父母都一樣。Though actually不過其實 many families never say "half-" at home很多家庭在家裡從來不講「half-」這個字。

If you grew up in the same house, you may just call him your brother, and that is warmth, not a mistake. People bring out half-brother when they need to be exact, or when they are explaining the family to someone new. It is an ordinary, polite word.

If you grew up in the same house如果你們是在同一個家裡長大的 you may just call him your brother你可能就直接叫他哥哥或弟弟 and that is warmth, not a mistake而這是親情，不是說錯話。People bring out half-brother大家會搬出 half-brother 這個字 when they need to be exact當他們需要講清楚的時候 or when they are explaining the family to someone new或是在跟不熟的人解釋家庭狀況的時候。It is an ordinary, polite word它是個平常又客氣的詞。

A stepbrother is different: he is the son of the person your mum or dad married later, so you are not blood relatives. A half-brother is.

A stepbrotherstepbrother（繼兄弟） is different不一樣：he is the son of the person your mum or dad married later他是你媽媽或爸爸後來再婚對象的兒子 so you are not blood relatives所以你們沒有血緣關係。A half-brotherhalf-brother is有血緣關係。