Volcanic/vɑːlˈkænɪk/ Definition 1 of 2Pro Tip 1/3Natural Occurrences Use 'volcanic' when describing natural events involving molten rock or geothermal energy. The volcanic landscape around Mount Fuji is breathtaking. Pro Tip 2/3Describing Rocks 'Volcanic' can describe rocks like basalt, formed from cooled lava. Her collection includes several volcanic stones. Pro Tip 3/3Figurative Use In non-literal usage, 'volcanic' suggests something as powerful or intense as a volcano. The machine had volcanic strength.