The word "un-diplomatic" implies a lack of tact, diplomacy or shrewdness. Its antonyms are words that describe the opposite attributes which include diplomatic, tactful, suave, respectful, careful, and polished. Diplomatic describes someone who has the ability to handle difficult situations with grace and diplomacy without causing offence. A tactful person is diplomatic and adeptly negotiates tricky situations. Someone who is suave is sophisticated, charming and polished, making them adept at dealing with others without causing offence. Respectful people are polite and courteous, showing appreciation for others' views, even when they disagree. Lastly, careful and polished people are meticulous in their language and behavior, making sure to avoid any unnecessary offense.