magma

American  

[mag-muh] / ˈmæg mə /

noun

• magmas,
  plural
• magmata
  plural

1. Geology. molten material beneath or within the earth's crust, from which igneous rock is formed.

2. any crude mixture of finely divided mineral or organic matter.

3. Chemistry, Pharmacology. a paste composed of solid and liquid matter.

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magma British  

/ ˈmæɡmə /

noun

1. a paste or suspension consisting of a finely divided solid dispersed in a liquid

2. hot molten rock, usually formed in the earth's upper mantle, some of which finds its way into the crust and onto the earth's surface, where it solidifies to form igneous rock

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magma Scientific  

/ măg′mə /

1. The molten rock material that originates under the Earth's crust and forms igneous rock when it has cooled. When magma cools and solidifies beneath the Earth's surface, it forms what are known as intrusive rocks. When it reaches the Earth's surface, it flows out as lava and forms extrusive (or volcanic) rocks.

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magma Cultural  

1. Molten rock usually located deep within the mantle of the Earth that occasionally comes to the surface through cracks in the mantle or through the eruption of volcano es.

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Usage

What’s the difference between magma and lava? Magma is what molten (melted) rock is called when it’s under the earth’s surface. Lava is what molten rock is called when it flows out of a volcano or volcanic vent. To be clear, in popular use, magma and lava 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 magma and lava 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 magma and lava.

Discover More

When magma cools and solidifies, it forms igneous rock, of which lava is one type.

Other Word Forms

Derived Forms

• magmatism
  noun
• magmatic
  adjective

Inflected Forms

Nouns

• magmas
  plural
• magmata
  plural

Etymology

Origin of magma

1400–50; late Middle English < Latin: dregs, leavings < Greek mágma kneaded mass, salve, equivalent to mag- (base of mássein to knead, press; see mass) + -ma noun suffix of result

Explanation

That red hot liquid rock that spews violently out of erupting volcanoes? That's lava. But before the lava rises to the earth's surface it's called magma. Although lava and magma are often used interchangeably, technically magma is the name for the hot molten rock (mixed with gases and mineral crystals) that collects in chambers beneath the Earth's crust. Once the magma breaks through the Earth's surface and flows down the volcano, you can call it lava. There are about 1500 active volcanoes on the Earth and at least 80 under the oceans — which add up to a lot of magma and possible lava.

Example Sentences

See Examples For:

magma magmas

The team proposes that a sheet of magma forced its way through layers of marine sediment at the Zaonega Formation, which at the time lay beneath a prehistoric ocean.

From Science Daily ● Sep. 26, 2026

Taken together with the shallow earthquakes and rapid uplift, the concern is that magma may be moving upwards.

From Science Daily ● Sep. 22, 2026

By reconstructing two major eruptions from the volcano's past, the scientists found that magma followed very different routes and moved toward the surface at very different speeds.

From Science Daily ● Sep. 14, 2026

Volcanoes are fed by enormous underground networks of magma and gas, but those systems do not always behave the same way.

From Science Daily ● Sep. 14, 2026

Orange-striped magma swirled and hissed around her, searching for a weak point in the metal casing.

From "Artemis Fowl" by Eoin Colfer

The main process enriching these magmas with gold appears to be high-degree, multi-stage melting of a water-rich and oxidized mantle.

From Science Daily ● Jul. 29, 2026

"We can therefore explain why some viscous magmas flow out gently instead of exploding, despite their high gas content -- a riddle that's been puzzling us for a long time," says Bachmann.

From Science Daily ● Nov. 22, 2025

He thinks that under the right conditions, similar light isotope ratios could have arisen in magmas interacting with seawater.

From Science Magazine ● Apr. 30, 2024

The chemical composition of the crystals, plucked from rocks in Australia, hint that they formed from magmas doped with freshwater, a team of scientists argues.

From Science Magazine ● Apr. 30, 2024

When magmas reach the surface red hot, they form extrusive rocks, such as volcanic rocks.

From Let's Collect Rocks and Shells by Shell Union Oil Corporation

Related Words

• basalt
• slag