a strange or unusual habit, way of behaving, or feature that someone or something has

She often cracks her knuckles when she's speaking - it's one of her little idiosyncrasies. 她讲话时常常将指节捏得咔咔作响，这是她的一个小怪癖。

One of the idiosyncrasies of this printer is that you can't stop it once it has started. 这台打印机的怪毛病之一是一旦开始打印就无法让它停下。