Unpleasantness is the quality of being disagreeable, uncomfortable, or difficult to experience. When there's unpleasantness in a situation, something about it bothers you or makes you want to avoid it. A dentist appointment might involve some unpleasantness, but you know it's necessary. The unpleasantness of a long, boring car ride comes from being stuck in one position with nothing interesting to do.

The word often describes social awkwardness or tension between people. If two friends have an argument and then try to act normal around each other, there might be an unpleasantness lingering in the air: that uncomfortable feeling that something isn't quite right. When adults say they want to “avoid any unpleasantness,” they mean they're trying to prevent disagreements or awkward situations from developing.

Sometimes people use the word as a polite way to refer to something more serious. In old novels, characters might refer to “the recent unpleasantness” when talking about a war or major conflict they'd rather not describe in detail. This understated usage makes a difficult topic easier to mention in conversation, like calling a terrible storm “a bit of bad weather.”