An eruption is a sudden, explosive burst or outbreak. The most familiar example is a volcanic eruption, when pressure builds up inside a volcano until molten rock, ash, and gas explode violently into the air. Mount Vesuvius famously erupted in 79 AD, burying the Roman city of Pompeii under layers of volcanic ash.

But eruption describes other kinds of sudden outbursts too. A geyser erupts when underground water heats up and shoots skyward. Your skin might have an eruption of pimples during adolescence. Laughter can erupt in a classroom when someone tells a hilarious joke: one moment it's quiet, the next moment everyone's laughing at once.

The word captures that sense of something building up pressure or tension until it suddenly breaks free. When a long, boring meeting finally ends, students might erupt from their seats, rushing toward the door. Conflict can erupt in a neighborhood when tensions boil over. Applause erupts when a performer finishes an amazing act.

Notice how eruption always suggests force and suddenness: things don't just happen, they explode into being.