Volcanic describes anything related to volcanoes or their activity. When scientists talk about volcanic eruptions, they mean the explosive release of melted rock, ash, and gases from deep inside the Earth. Volcanic rock forms when this molten material, called lava, cools and hardens.

Volcanic landscapes often look dramatic and otherworldly. The Hawaiian Islands are entirely volcanic, built up over millions of years by underwater eruptions. Iceland sits on a volcanic hotspot where the Earth's crust is particularly thin, making it one of the most volcanically active places on the planet. Mount Vesuvius, a famous volcanic mountain in Italy, buried the ancient city of Pompeii in ash nearly 2,000 years ago.

The word also describes explosive or intense behavior, like when someone has a volcanic temper that erupts suddenly. You might say tensions in a classroom became volcanic before finally boiling over into an argument.

While volcanic eruptions can be destructive, they also create some of Earth's most fertile soil. Many of the world's best farmlands exist on volcanic terrain because the minerals from ancient eruptions enriched the ground. That's why people have lived near volcanoes for thousands of years, despite the danger.