The Collaborative International Dictionary
Volcanism \Vol"can*ism\, n. Volcanic power or action; volcanicity.
Douglas Harper's Etymology Dictionary
1819, from French volcanisme, from volcan (see volcano).
Wiktionary
n. (context volcanology English) Any of the natural phenomena and processes associated with the action of volcanos, geysers and fumaroles
WordNet
n. the phenomena associated with volcanic activity
Wikipedia
Volcanism is the phenomenon of eruption of molten rock ( magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics and volcanic gases erupt through a break in the surface called a vent. It includes all phenomena resulting from and causing magma within the crust or mantle of the body, to rise through the crust and form volcanic rocks on the surface.
Usage examples of "volcanism".
The geyserite implied volcanism beneath, and also intermittent steam eruptions, which might have been what they had seen the night before.
But volcanism in the north was due to subduction zones, crustal plates moving together from opposite directions.
The air had been black and turgid, corrupt with the belchings of volcanism, and blue skies had lain far in the future.
Meanwhile, what are we to conclude about the apocalyptic visions of fire and ice, floods, volcanism and earthquakes, which the myths contain?
We do not even today understand the connection between the size and structure of a planet and the presence of volcanism and mountains, although we do know that there are no significant folded mountain ranges on the Moon.
And already Henry could see Jays Malone's rille: Schröter's Valley, a dry valley gouged into the sandy surface of the Moon by a brief, late spasm of lunar volcanism.
A vast line of earthquakes and ugly volcanism was unstitching an eastern continent.