This is the 658th most frequent Chinese word.
道德
Morality; ethics.
Here, 道德 is used as a noun, referring to the concept or principle of morality.
道德是社会行为的规范。
Morality is the standard of social behavior.
In this sentence, 道德 is used as a modifier to describe the moral dimension of his honesty.
他在道德上表现出极大的诚实。
He displayed great honesty in terms of morality.
Here, 道德 is an attributive noun describing the type of responsibility being discussed.