1 a : of, relating to, or having the characteristics of advanced culture b : marked by refined cultural interests and pursuits especially in arts and belles lettres
2 a : showing or characterized by correct social usage b : marked by an appearance of consideration, tact, deference, or courtesy c : marked by a lack of roughness or crudities
Politeness is best expressed as the practical application of good manners or etiquette. It is a culturally defined phenomenon, and therefore what is considered polite in one culture can sometimes be quite rude or simply strange in another cultural context.
While the goal of politeness is to make all of the parties relaxed and comfortable with one another, these culturally defined standards at times may be manipulated to inflict shame on a designated party. (via Wikipedia)