pyroclastic

adjective

py·​ro·​clas·​tic ˌpī-rō-ˈkla-stik How to pronounce pyroclastic (audio)
: formed by or involving fragmentation as a result of volcanic or igneous action

Examples of pyroclastic in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Bright-red pyroclastic material extends for at least 186 miles (300 km) around the vent. — Atharva Gosavi, Interesting Engineering, 22 Aug. 2026 This was promptly followed by rapidly moving ground-hugging clouds of blistering hot gas and rock fragments, a phenomenon called pyroclastic flow. — Britannica Editors, Encyclopedia Britannica, 18 Aug. 2026 The eruption started Monday morning, with clouds of gas and ash rising above the volcano as lava and pyroclastic flows rolled down the slopes. — ABC News, 4 Aug. 2026 Based on reconstructions, Jackson estimates that the pyroclastic flows would be moving between 100 and 200 kilometers per hour (60–120 mph). — ArsTechnica, 21 July 2026 See All Example Sentences for pyroclastic

Word History

Etymology

probably from pyro- + clastic

Note: The term was introduced by the English geologist Joseph Beete Jukes (1811-69) in The Student's Manual of Geology, new edition (Edinburgh, 1862), p. 68: "The word 'ash' is not a very good one to include all the mechanical accompaniments of a subaerial or subaqueous eruption, since ash seems to be restricted to a fine powder, the residuum of combustion. A word is wanting to express all such accompaniments, no matter what their size or condition may be, when they are accumulated in such mass so as to form beds of 'rock.' We might call them perhaps 'pyroclastic materials'… ." In the index pyroclastic is glossed as "broken from fire."

First Known Use

1862, in the meaning defined above

Time Traveler
The first known use of pyroclastic was in 1862

Rhymes for pyroclastic

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Browse Nearby Words

pyroclast
pyroclastic
pyrocoll
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Cite this Entry

“Pyroclastic.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/pyroclastic. Accessed 1 Sep. 2026.

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