English Reference

Word

magma

Phoneticsmag·ma

US/ˈmæɡmə/

UK/mˈæɡmɐ/

Definitions

01molten rock

B2 · Science

n. hot, liquid rock that is found under the surface of the Earth.

n. a mixture of molten rock, crystals, and dissolved gases located beneath the Earth's crust.

“Magma collects in large chambers deep underground before a volcanic eruption.”

“Geologists monitored the movement of magma within the subterranean chamber, looking for pressure changes that might indicate an imminent eruption.”

Technical

Usage

Uncountable when referring to the substance generally; countable when referring to specific bodies of molten rock.

Pitfall

The volcano erupted magma all over the village.

The volcano erupted lava all over the village.

Use 'magma' for molten rock underground and 'lava' once it reaches the surface.

Synonyms

molten rock

02algebraic structure

C2 · Math

n. a basic set in math that has one way to combine two of its elements.

n. a basic algebraic structure consisting of a set equipped with a single binary operation.

“In our advanced algebra class, we learned that a magma is the simplest kind of algebraic system.”

“The researcher demonstrated that the set, under the defined operation, satisfied the requirements of a magma but lacked the associativity needed to be a semigroup.”

Technical · Academic

Usage

Countable noun in mathematical contexts.

Synonyms

groupoid

03doughy mass

C2

n. any soft, thick, or wet mixture of solid and liquid.

n. a soft, doughy, or pasty mass of matter.

“The chemist stirred the thick magma until it became a smooth paste.”

“After the juice was extracted, a thick magma of fruit pulp remained at the bottom of the press.”

Archaic · Technical

Teaching tip

This sense is rare in modern general English and is mostly found in older scientific or pharmaceutical texts.

Synonyms

Real-World Examples

“Around 74,000 years ago, a caldera on what is now Sumatra emptied thousands of cubic kilometers of magma in about two weeks, roughly a thousand times more than Mount Pinatubo spewed out in 1991.”
Ars Technica · 9 Aug 2026
“Over geological timescales, a magma body of this size could theoretically play a role in the development of a supervolcano.”
ScienceDaily · 5 Aug 2026
“Scientists studying magma from the 2021 Tajogaite eruption on La Palma have discovered that extreme heat can dramatically change how an eruption unfolds.”
ScienceDaily · 1 Aug 2026
“Although that amount may sound tiny, it is unusually high for mantle-derived magma.”
ScienceDaily · 29 Jul 2026

Etymology

Etymology tree Proto-Indo-European *mh₂ǵyéti Ancient Greek μάσσω (mássō) Proto-Indo-European *-mn̥ Ancient Greek -μα (-ma) Ancient Greek μάγμα (mágma)der. English magma From Ancient Greek μάγμα (mágma, “paste”).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Domains

GeologyMathematics

This entry

Level
C1 · Advanced
Frequency
Occasional
Updated

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