magma

[ mag-muh ]

noun

, plural mag·mas, mag·ma·ta [mag, -m, uh, -t, uh].

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.

magma

/ 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

magma

/ măg′mə /

, or magmas

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.

magma

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.

Notes

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

Derived Forms

• ˈmagmatism, noun
• magmatic, adjective

Other Words From

• mag·mat·ic [mag-, mat, -ik], adjective
• magma·tism noun

Word History and Origins

Origin of magma¹

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

Word History and Origins

Origin of magma¹

C15, from Latin: dregs (of an ointment), from Greek: salve made by kneading, from massein to knead

Example Sentences

That can cause the dynamic subterranean forces below volcanoes to produce increased quantities of magma, leading to more frequent eruptions.

From Salon

“We'd like to instrument the magma so we can really listen to the pulse of the earth,” he adds.

From BBC

The findings back up a theory that magma formed the Moon's surface around 4.5 billion years ago.

From BBC

“If it were due to magma that was rising up underneath the ground, we would see really spectacular changes,” Poland said.

From Los Angeles Times

Tectonics starts with superheated plumes of magma from close to Earth’s core rising and sitting beneath the planet’s plates.

From New York Times

Related Words

• basalt
• slag

Magma Vs. Lava

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.

Quiz yourself on magma vs. lava!

Should magma or lava be used in the following sentence?

The eruption resulted in a steady flow of _____ from the volcano.