Nastiness is the quality of being deliberately mean, unpleasant, or cruel. When someone speaks with nastiness, they're trying to hurt someone's feelings or make them uncomfortable on purpose, going beyond what honesty or directness requires. A comment delivered with nastiness has extra bite to it, like adding poison to words that could have been said kindly.

You can see nastiness in how someone treats others. A student might answer a question correctly but with such nastiness toward the person who asked that everyone feels uncomfortable. Nastiness shows up in sneering tones, cutting remarks, and actions designed to make others feel small or embarrassed.

The word also describes something physically disgusting or revolting. The nastiness of rotting garbage or a grimy, neglected bathroom can make people want to look away. A nasty cut or wound looks bad enough to make you wince.

What makes nastiness different from ordinary rudeness is its intentional quality. Someone having a bad day might be accidentally rude, but nastiness involves choosing to be mean or revolting.