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"