'Magma' definitions:

Definition of 'magma'

noun

Molten rock in the earth's crust

From: GCIDE

Magma \Mag"ma\, n. [L., fr. Gr. ?, fr. ? to squeeze, knead.]
1. Any crude mixture of mineral or organic matters in the state of a thin paste. --Ure. [1913 Webster]
2. (Med.) (a) A thick residuum obtained from certain substances after the fluid parts are expressed from them; the grounds which remain after treating a substance with any menstruum, as water or alcohol. (b) A salve or confection of thick consistency. --Dunglison. [1913 Webster]
3. (Geol.) (a) The molten matter within the earth, the source of the material of lava flows, dikes of eruptive rocks, etc. (b) The glassy base of an eruptive rock. [1913 Webster]
4. (Chem.) The amorphous or homogenous matrix or ground mass, as distinguished from well-defined crystals; as, the magma of porphyry. [1913 Webster] Magna Carta