1.
lack of virtue; immorality; personal failing
A formal term for moral failings or shortcomings in character. Most commonly encountered in the set phrase of apology: "owing to my lack of virtue."
Usage
不徳 is almost always encountered in the fixed expression 不徳の致すところ, a very formal apology meaning "it is the result of my lack of virtue / personal failings." This phrase is commonly used by politicians, executives, and public figures when taking responsibility for scandals or mistakes.
Fixed pattern
不徳の致すところです — a humble expression accepting full blame. The phrase implies that the speaker's personal moral shortcomings led to the unfortunate outcome.
Register
This is a very formal, humble expression used in public apologies. It would not be used in casual conversation.