N-PLURAL
（某组织或团体的）成员，会员；（尤指宗教团体的）教友
You can refer to the members of a particular organization or group, especially a religious group, as brethren.
例句
We must help our brethren, it is our duty...
我们必须帮助我们的教友，这是我们的责任。
Sri Lankans share a common ancestry with their Indian brethren.
斯里兰卡人和他们的印度兄弟有共同的祖先。