1. Any crude mixture of mineral or organic matters in the state of a thin paste.
2. (Science: medicine) 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. A salve or confection of thick consistency.
3. (Science: geology) The molten matter within the earth, the source of the material of lava flows, dikes of eruptive rocks, etc. The glassy base of an eruptive rock.
4. (Science: chemistry) The amorphous or homogenous matrix or ground mass, as distinguished from well-defined crystals; as, the magma of porphyry.
Origin: L, fr. Gr, fr. To squeeze, knead.