Capacity is the ability to hold something, very similar to volume.
Capacity may also mean:
Capacity in economics, how much a company or a government uses its potential output Capacitythe legal ability to do certain things, such as making a contract Capacity of a set, in mathematics, one way of measuring a set's size Battery capacity, a measure of a battery's ability to store electrical charge Carrying capacity, in biology, the ability of an environment to sustain populations Channel capacity, in communications Combining capacity, in chemistry, number of chemical bonds formed by the atoms of a given element Heat capacity, in physics, the measure of how materials store heat as they change temperature Nameplate capacity, in power plants, the general number of Megawatts technically available Seating capacity, how many people can fit into in a sports venue