Pyroclastic

Part of speech: adjective

Definitions

1. Referring to volcanic fragments that are expelled during an eruption
2. Involving fast-moving currents of hot gases mixed with volcanic particles released from a volcano
3. Concerning fragments of rock and ash thrown out by volcanic activity ; related to swift clouds of gas and volcanic material moving down a volcano's slopes

Etymology: "Pyroclastic" is built from two Ancient Greek words: "pûr", meaning fire, and "klastós", meaning broken. The Greek roots reach English through a scientific route rather than everyday speech, so the word reads as a compound of "pyro-" (fire) and "clastic" (broken into fragments), with the second part carrying the sense of fragmentation. The combination describes rock and debris that is shattered by volcanic eruption. A pyroclastic flow, for instance, is a fast-moving mass of hot gas and rock fragments, and the adjective names materials formed in this way. Geologists needed a precise term for rock created by blasting apart, distinct from rock that had merely been melted or cooled, and assembling the word from classical parts gave them one that described the process directly.

Synonyms: volcanic, explosive, fiery