What term describes a glaringly bad action or violation?

The term "flagrant" specifically conveys the idea of an action that is conspicuously bad or outrageous. It carries a strong connotation of something that is not only wrong but done with a lack of regard or obviousness, making it stand out as particularly unacceptable. This word is often used in contexts where the severity or boldness of the violation is so apparent that it demands attention.

In contrast, terms like "affront," "offensive," and "serious" do not capture the same degree of glaring disregard. "Affront" refers more to a personal insult or offense, rather than the blatant nature of an action. "Offensive" describes something that causes displeasure or resentment, but it lacks the specific indication of brazen disregard found in "flagrant." "Serious" conveys a sense of importance or gravity but does not imply the same level of overt wrongdoing. Therefore, "flagrant" is the most fitting choice to describe a glaringly bad action or violation.