Pre-eruption lava is the molten rock that exists beneath the surface of the Earth before it is expelled during a volcanic eruption. It is also known as MAGMA, which is the five-letter word used in the crossword solution. MAGMA is composed of minerals and gases and is formed when the Earth's mantle melts due to extreme heat and pressure. It is then forced up through the Earth's crust and can be seen as lava when it reaches the surface.