Definition of Plutonist in US English:

Plutonist

noun

historical
  • An advocate of Plutonism, the theory (now accepted) that rocks such as granite were formed by solidification from the molten state rather than by precipitation from the sea.

    ‘as regards the origin of basalt and granite, the Plutonists had secured a victory by 1820’

adjective

historical
  • Relating to Plutonism, the theory (now accepted) that rocks such as granite were formed by solidification from the molten state rather than by precipitation from the sea.

    ‘he published his Plutonist description of Salisbury Crags’

Pronunciation

Plutonist

/ˈplo͞otənəst//ˈplutənəst/