definition
(Greek mythology, Roman mythology) Of or relating to Pluto, the Greek and Roman god of the underworld; demonic, infernal.
definition
(by extension) Of, relating to, or having characteristics associated with the underworld; dark, gloomy; mournful.
definition
(by extension, geology) Synonym of plutonic (“of or pertaining to rocks formed deep in the Earth's crust, rather than by volcanoes at the surface of the Earth”)
definition
(by extension, geology, historical) Synonym of plutonic (“of, pertaining to, or supporting plutonism, the theory that the rocks of the Earth were formed in fire by volcanic activity, with a continuing gradual process of weathering and erosion, then deposited on the sea bed, re-formed into layers of sedimentary rock by heat and pressure, and raised again”)