1. Pertaining to, having the nature of, fire; containing fire; resembling fire; as, an igneous appearance.
2. (Science: geology) Resulting from, or produced by, the action of fire; as, lavas and basalt are igneous rocks.
Origin: L. Igneus, fr. Ignis fire; allied to Skr. Agni, lith. Ugnis, OSlav. Ogne.