- (countable); (geology) Lava is the molten rock that is spit out of a volcano when it erupts.
- When the volcano erupted, it spit out lots of lava.
- (uncountable); (geology) Lava is magma that is found on the surface of the Earth.
Note: Lava is different than magma. Magma is molten rock that is under the surface of the Earth, while lava is molten rock that is on the surface of the Earth.