Which term describes someone who is stubborn and disobedient, particularly in resisting authority?

The term "contumacious" is the most suitable choice to describe someone who is stubborn and disobedient, especially in their resistance to authority. This word originates from the Latin "contumax," which means rebellious or disobedient. It specifically captures the essence of defying or ignoring directives from those in positions of power, emphasizing a wilful refusal to comply.

In contrast, the other options present different meanings. "Captious" refers to someone who tends to find fault or raise trivial objections, which does not necessarily imply outright defiance. “Calumny” relates to making false statements about someone in order to damage their reputation, and it does not connect to disobedience. Meanwhile, "cavil" means to make petty or trivial objections without engaging in the substantive issues at hand, again lacking the rebellious undertone that "contumacious" embodies. Thus, "contumacious" effectively conveys the idea of a person who is not only stubborn but actively resists complying with authority.