1. [ adjective ] (geology) igneous rock that has solidified beneath the earth's surface; granite or diorite or gabbro
Synonyms: plutonic irruptive
Related terms: intrusive
2. [ adjective ] (geology) igneous rock produced by eruption and solidified on or near the earth's surface; rhyolite or andesite or basalt
Synonyms: volcanic

"volcanic rock includes the volcanic glass obsidian"

Related terms: extrusive
3. [ adjective ] erupting or tending to erupt
Synonyms: erupting

"a geyser is an intermittently eruptive hot spring" "people fled from the erupting volcano"

Related terms: active
Similar spelling:   erupt