magma

American  

[mag-muh] / ˈmæg mə /

noun

plural

magmas, magmata

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, mæɡˈmætɪk /

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

• magmatic adjective
• magmatism noun

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

The magma currently present does not appear to be leftover from the earlier eruption.

From Science Daily • Mar. 29, 2026

Researchers suggest that L 98-59 d may be the first identified example of a broader population of gas rich sulfur dominated planets that sustain long lived magma oceans.

From Science Daily • Mar. 17, 2026

At the same time, the magma ocean below acts as a massive storage system for volatile materials, absorbing and releasing gases over billions of years after the planet formed.

From Science Daily • Mar. 17, 2026

The "Jerk" method identifies extremely small ground motions that occur when magma intrudes into the crust.

From Science Daily • Mar. 15, 2026

Rock from the subducting plate melts when it reaches the mantle, creating hot spots of magma.

From "Meltdown" by Deirdre Langeland

Related Words

• basalt
• slag