Capacity is a term that can refer to:

1. The amount of electrical energy a cell or battery contains expressed in ampere-hours.
2. The power of receiving or containing; extent of room or space; passive power; -- used in reference to physical things.

3. The power of receiving and holding ideas, knowledge, etc.; the comprehensiveness of the mind; the receptive faculty; capability of understanding or feeling.
4. Ability; power pertaining to, or resulting from, the possession of strength, wealth, or talent; possibility of being or of doing.
5. Ability; faculty; talent; capability; skill; efficiency; cleverness.
Ex. specific heat capacity? (Or specific heat.) The heat capacity of a system divided by its mass.