# magma

/ˈmæɡmə/ (US) · /mˈæɡmɐ/ (UK)

Source: https://englishreference.com/word/magma
Updated: 2026-08-27

## Senses

### 1. molten rock

noun · CEFR B2 · Technical

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

For teachers: 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.

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

### 2. algebraic structure

noun · CEFR C2 · Technical · Academic

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

For teachers: 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.

Usage: Countable noun in mathematical contexts.

### 3. doughy mass

noun · CEFR C2 · Archaic · Technical

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

For teachers: 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.

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

## Examples

- Magma flows deep beneath the surface of the volcano.
- Geologists use seismic waves to map the movement of magma within the chamber before an eruption occurs.
- The chemical composition of the magma determines the viscosity of the eventual flow, with silica-rich mixtures resulting in more explosive volcanic events.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.