Which attribute describes someone who is unrefined or coarse in manner?

The term that best describes someone who is unrefined or coarse in manner is "plebeian." This word originates from ancient Rome, where it referred to the common people and their lifestyles, which were often viewed as lacking the sophistication or cultural refinement of the elite classes. In a modern context, labeling someone as plebeian suggests that they possess a certain roughness or lack of polish in behavior and mannerisms, embodying characteristics that might be considered less cultured or aristocratic.

Ponderous typically refers to something that is heavy or cumbersome, not specifically relating to a person's manners. Nonchalant describes a demeanor that is casually calm and relaxed, suggesting a lack of concern rather than coarseness. Mollify means to soothe or calm someone, which is unrelated to the concept of being unrefined. Therefore, the choice of "plebeian" directly captures the essence of unrefinement in behavior and attitude.