兄弟用英文说是brother。
brothers n.兄弟；教友；同胞；（brethren的复数）。
younger brother 弟弟；小弟；年轻的弟弟。
fraternal adj.兄弟的；兄弟般的；异卵双生的；兄弟会的；协会的。
brotherly adj.兄弟的；兄弟般的；亲切的。
从堂兄弟
male cousins
兄弟俩
the two brothers
师兄弟
fellow apprentices; male apprentices of the same master;fellow (male) students
兄弟情分
fraternity; brotherhood
双生兄弟
twin brothers
拜把子兄弟
sworn brother
骨肉兄弟
blood brothers; one's own brother
异姓兄弟
sworn brothers of different surnames
兄弟关系
brotherhood
三胞胎兄弟
triplet brothers
兄弟姐妹
brothers and sisters; siblings
远门兄弟
distant cousin
四海之内皆兄弟
all men are brothers within the four seas; all the people in the world are brothers
本家兄弟
brothers of the same clan
孪生兄弟
twin brothers
结义兄弟
sworn brothers
兄弟民族
other ethnic groups
兄弟姐妹们
brothers and sisters
自己兄弟
one's own brothers
王氏兄弟
Wang brothers
双语例句：
1、我兄弟是个火爆性子，一点就着。
My brother’s got a fiery temper and flares up at the slightest provocation.
2、从他们的长相上看，不像兄弟俩。
They don’t look like brothers.
3、兄弟俩为父亲留下的遗产闹矛盾。
The two brothers fell out with each other over an inheritance from their father.
4、经他荐引，我兄弟被耶鲁大学录取。
With his recommendation, my brother was admitted into Yale University.
5、对他们兄弟俩你要一碗水端平。
You should treat the two brothers equally/fairly.
6、她的两个兄弟已经分居并自立门户。
Her two brothers have set up their own homes.
7、他们兄弟般地一起生活和工作。
They live and work together like brothers.
8、他们兄弟之间个性差别很大。
The two brothers are markedly dissimilar in character.
9、兄弟俩的模样长得一模一样。
The two brothers are cast in the same mould.
10、这对孪生兄弟惊人地相像。
There was an amazing similarity between the twin brothers.