"沉溺于"的意思是"to become deeply absorbed or involved in something, often to the exclusion of other things"，也就是专注于某件事情，常常忽略其他事情。这个短语可以用来形容人们对于某种兴趣、爱好、工作等等非常专注、沉迷。

例如：

他沉溺于音乐，常常在家里整整弹了一天的钢琴。（He becomes deeply absorbed in music, often playing the piano for hours at home.）
她沉溺于电视剧，整天看到深夜都不想睡觉。（She becomes deeply absorbed in TV dramas, watching them until late at night without wanting to sleep.）