lava
Americannoun
-
the molten, fluid rock that issues from a volcano or volcanic vent.
-
the rock formed when this solidifies, occurring in many varieties differing greatly in structure and constitution.
noun
-
magma emanating from volcanoes and other vents
-
any extrusive igneous rock formed by the cooling and solidification of molten lava
-
Molten rock that flows from a volcano or from a crack in the Earth. Most lava flows at a rate of a few kilometers per hour, but rates as high as 60 km (37 mi) per hour have been observed. Lava that contains abundant iron- and magnesium-rich components usually erupts with temperatures between 1,000°C and 1,200°C (1,832deg;F and 2,192°F). Lava that contains abundant silica- and feldspar-rich components usually erupts with temperatures between 800°C and 1,000°C (1,472deg;F and 1,832°F).
-
Compare magma
-
The igneous rock formed when this substance cools and hardens. Depending on its composition and the rate at which it cools, lava can be glassy, very finely grained, ropelike, or coarsely grained. When it cools underwater, it cools in pillow-shaped masses.
-
See also aa pahoehoe pillow lava
Usage
What’s the difference between lava and magma? Lava is what molten (melted) rock is called when it flows out of a volcano or volcanic vent. Magma is what molten rock is called when it’s under the earth’s surface.To be clear, in popular use, lava and magma are essentially different names for the same liquid-hot, charred orange ooze—which name is used depends on whether it is above or below the surface.However, geologists and volcanologists have their reasons for using the two different terms to distinguish between forms of what is the same substance.Magma doesn’t always become lava—sometimes it cools and solidifies beneath the earth's surface. Sometimes, it collects in what’s known as a magma chamber. When it does reach the surface, it flows out as lava. The rock that’s formed when it hardens and cools can also be called lava, though this use of the term is uncommon outside of technical, scientific contexts.The word lava is perhaps the more well-known of the two because that’s the one we see when volcanoes erupt (or when the floor turns into it).Here is an example of lava and magma used correctly in the same sentence.Example: Lava began flowing from the volcano three days after scientists detected movement of magma underground.Want to learn more? Read the full breakdown of the difference between lava and magma.
Etymology
Origin of lava
1740–50; < Italian, originally Neapolitan dialect: avalanche < Latin lābēs a sliding down, falling, akin to lābī to slide
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Snaking through dunes, mountains and lava fields, the pipeline carries oil from huge fields in eastern Saudi Arabia to the country’s Red Sea Coast.
From The Wall Street Journal • Mar. 11, 2026
Early activity involved lava spreading out from fissures in the ground, while later eruptions came from more focused vents that built cone shaped features.
From Science Daily • Feb. 23, 2026
It's unclear what started the fires, but to put them out, workers had to remove tonnes of "molten lava" from deep below the surface.
From BBC • Feb. 12, 2026
These factors could help molten lava quickly form a thick insulating crust once it flows away from its source, preserving broad underground channels.
From Science Daily • Feb. 12, 2026
Just as the Witchlings began to make a run for it, the cuco shrieked loudly and ran through the lava, straight at them.
From "Witchlings" by Claribel A. Ortega
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
