Which geological concept refers to material ejected from a volcano?

The term that best describes material ejected from a volcano is "tephra." Tephra refers to a variety of volcanic materials, including ash, pumice, and volcanic bombs, that are expelled during an explosive volcanic eruption. This material can vary in size and composition, and it is classified based on its particle size, with ash being the finest and volcanic bombs being larger fragments.

While "lava" refers specifically to molten rock that is expelled from a volcano during an effusive eruption when it reaches the Earth's surface, it does not encompass the broader category of materials expelled during explosive eruptions. "Magma" refers to molten rock that is below the Earth's surface before it erupts, which is not ejected until it becomes lava. "Pumice" is a type of tephra that is specifically a light, porous form of volcanic glass formed during explosive eruptions but does not include all the other materials that can be ejected. Therefore, tephra is the most comprehensive term for all material ejected during volcanic activity.