Definition - What does Rock mean?
Rock is a solid material made from minerals, which forms part of the earth's surface and lies under soil or extends out from it. Rock has various forms of composition and has three primary means of formation that result in three main, different types of rock. The three types of rock are igneous, metamorphic and sedimentary, which are all created under different conditions.
Safeopedia explains Rock
Igneous rock is formed when lava or magma cools and solidifies. It may crystallize in this process. Metamorphic rock is formed as a sedimentary or igneous rock is subject to chemical alteration by heat and pressure and is compressed to a denser form. Sedimentary rock is formed when other types or rock are broken down into particles by wind, ice, water flow etc and are deposited together, solidified or cemented into one solid mass.