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"
explosively unstable; "a volcanic temper"
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"
a high gear used at high speeds to maintain the driving speed with less output power
the state of high or excessive activity or productivity or concentration; "Troops are ready to go into overdrive as soon as the signal is given"; "Melissa's brain was in overdrive"
drive or work too hard; "The teacher is overworking his students"; "Overdriving people often suffer stress"