Which word can be used to describe someone lacking refinement or polish?

The term that best describes someone lacking refinement or polish is "boorish." This word characterizes behavior that is rude, clumsy, or lacking social graces. Someone described as boorish would typically display a lack of manners or sophistication, often resulting in an awkward or unrefined demeanor in social situations.

"Bourgeois" refers to the middle class and often carries connotations of being materialistic or conventional, but it does not directly imply a lack of refinement.

"Catharsis" denotes an emotional release or purification, often through art or literature, and is unrelated to social behavior or refinement.

"Cogent" describes an argument or case that is clear, logical, and convincing, emphasizing rational thought rather than personal qualities or manners.

Therefore, "boorish" distinctly captures the idea of a person who is unrefined and lacking in social polish.