Final answer:
A relatively small, summit depression on a volcano, marking a former eruptive vent, is a crater.
Step-by-step explanation:
A relatively small, summit depression on a volcano, marking a former eruptive vent, is called a crater. It is created when volcanic eruptions expel material such as lava, ash, and gases from the interior of the Earth.
The expelled material leaves behind a depression in the shape of a bowl or cauldron.