1.Definition: explosively unstable
"A volcanic temper"
2.Definition: igneous rock produced by eruption and solidified on or near the earth's surface; rhyolite or andesite or basalt
"Volcanic rock includes the volcanic glass obsidian"
3.Definition: relating to or produced by or consisting of volcanoes
"Volcanic steam", "Volcanic islands such as Iceland", "A volcanic cone is a conical mountain or hill built up of material from volcanic eruptions"