definition
(Greek mythology, Roman mythology) Synonym of Plutonian (“of or relating to Pluto, the Greek and Roman god of the underworld; demonic, infernal”)
definition
(by extension) Synonym of Plutonian (“of, relating to, or having characteristics associated with the underworld; dark, gloomy; mournful”)
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(by extension, geology, mineralogy) Of or pertaining to rocks formed deep in the Earth's crust, rather than by volcanoes at the surface of the Earth.
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(by extension, geology, historical) 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”).