The adjective cultivated is used to describe someone who is polite and civilized. The cultivated people at the party would be very offended by crude behavior.
Someone who's cultivated is knowledgeable or at least familiar with the arts, current events, history. He or she probably has traveled widely, or at least has read about other people and places. In other words, a cultivated person is a citizen of the world. As it applies to farming, cultivated soil is tilled, or churned, to prepare it for planting.