寂寞用英语可以说为 "loneliness". 这个词来源于古英语中的 "lonelīc"，意思是 "独自一人"。例句：

She felt a deep sense of loneliness after her husband passed away. 她在丈夫去世后感到一种深深的寂寞。

Loneliness can be a difficult feeling to shake off. 寂寞可能是一种难以摆脱的感觉。

He sought refuge from his loneliness in books. 他在书中寻找寂寞的慰藏。