n.

1. 不忠，不貞[U]
   I felt that disobedience was disloyalty to my father.

   我覺得不服從就是對我父親的不忠。

2. 不忠的行為[C][（+to）]
   His regret was for his disloyalty to one who had saved the lives of every member of his family.

   他悔恨的是他對那個曾經救了他全家生命的人的不忠行為。