Definition of volcanist in US English:

volcanist

noun

Geology
  • 1Also with capital initial. A person who attributes the origin of basalt and other crystalline rocks to volcanic action or to igneous processes in general (now historical); contrasted with "Neptunist". Also in extended use: a person who attributes certain features or phenomena (as craters or mass extinctions) to volcanoes.

  • 2A person who studies volcanoes; a volcanologist. Now rare.

Origin

Late 18th century; earliest use found in The Critical Review. From volcan- + -ist, originally after French volcaniste.

Pronunciation

volcanist

/ˈvɒlkənɪst/