Vent - An opening, as in a wall, serving as an outlet for air, smoke, fumes, or the like. 

Crater - A bowl-shaped geological formation at the top of a volcano. 

Lava Flow - A stream or sheet of molten or solidified lava. 

Sill - An intrusive body of magma that pushes its way between layers of sediments. 

Ash Cloud - Cloud of gas, steam, ash, dust, and coarser fragments that form during an explosive volcanic eruption and commonly gets blown long distances. 

Secondary Vent - A secondary vent is a vent or tube that connects to the secondary cone for the lava to flow. 

Throat - Entrance of a volcano. The part of the conduit that ejects lava and volcanic ash. 

Conduit - An underground passage magma travels through. 

Magma Chamber - A reservoir of magma in the earth's crust where the magma may reside temporarily on its way from the upper mantle to the earth's surface.