Which word best describes a person who is polite and refined in manner?

The word "urbane" is best suited to describe a person who exhibits politeness and refinement in their manner. This term carries connotations of sophistication and smoothness in social interactions, often associated with someone who is well-educated and cultured. An urbane individual demonstrates a certain level of grace and an understanding of social etiquette, making them adept at navigating social situations in a polished manner.

In contrast, while "social" may refer to someone who enjoys engaging with others, it does not inherently imply refinement or politeness. The term "cordial" describes a warm and friendly demeanor, which is certainly positive but may not encompass the broader sophistication suggested by "urbane." Lastly, "casual" typically indicates a relaxed, informal attitude, which stands in stark contrast to the polished and refined qualities associated with an urbane individual.