Definition of igneous

Said of a rock or mineral that solidified from molten or partly molten material, i.e., from a magma; also, applied to processes leading to, related to, or resulting from the formation of such rocks. Igneous rocks constitute one of the three main classes into which rocks are divided, the others being metamorphic and sedimentary. Etymol: Latin ignis, fire.

See Also: magmatic, plutonic, pyrogenic, hypabyssal, extrusive

Ref: AGI