a.[Z]

1. 無窮盡的；經久不衰的
   He could not have succeeded without the unfailing support of his wife.

   若沒有他妻子始終如一的支持，他是不可能成功的。

2. 可靠的
   an unfailing friend

   忠實的朋友

adj.

1. without error.
2. reliable or constant.