A body of magma that rises from the Earth's mantle into the crust. ◇ If a plume rises to the Earth's surface, it erupts as lava. ◇ If it remains below the Earth's surface, it eventually solidifies into a body of rock known as a pluton.
An area in air, water, soil, or rock containing pollutants released from a single source. A plume often spreads in the environment due to the action of wind, currents, or gravity.