volcano definition. A cone-shaped mountain or hill created by molten material that rises from the interior of the Earth to the surface. Note: Volcanoes tend to occur along the edges of tectonic plates. Note: Eruptions and lava flows associated with them can be very destructive.
A volcano is a vent in the earth's crust through which lava, rock fragments, hot vapor and gases are ejected. A volcano begins to form when magma, which is hot molten rock from deep within the earth, rises toward the earth's surface and collects in magma chambers.