Which term describes a person who leaves a group and acts in a traitorous manner?

The term "renegade" is used to describe a person who betrays or abandons a particular group, cause, or set of principles, often acting in a traitorous manner. This term conveys a sense of rebellion or defiance against previously held loyalties, emphasizing the idea of someone who has turned away from accepted norms or allegiances. In contexts where loyalty is expected, a renegade can be viewed as untrustworthy or disloyal, often seeking out a new path or ideology that goes against the grain of their former affiliations.

In contrast, the other terms do not convey the same meaning. "Martinet" refers to a strict disciplinarian, particularly in a military context, which does not imply betrayal. "Vociferous" describes someone who is loud and forceful, especially in expression, while "somber" relates to a serious or gloomy disposition. These words focus on different characteristics and do not capture the concept of disloyalty or betrayal inherent in the term "renegade."