a.

1. 疼痛的；引起痛苦的
   My back is so painful that I cannot stand upright anymore.

   我的背疼痛难忍，我现在甚至站不直了。

2. 费力的；困难的；麻烦的
3. 令人不快的；恼人的
   It was painful to admit that I was wrong.

   承认我自己错了是件很痛苦的事。

4. 【古】细心的；辛勤的

adj.

1. affected with or causing pain.
2. informal embarrassingly bad or inept.