—n. 1. the ability to receive or contain: This hotel has a large capacity. 2. the maximum amount or number that can be received or contained; cubic contents; volume: The inn is filled to capacity.The gasoline tank has a capacity of 20 gallons. 3. power of receiving impressions, knowledge, etc.; mental ability: the capacity to learn calculus. 4. actual or potential ability to perform, yield, or withstand: He has a capacity for hard work. The capacity of the oil well was 150 barrels a day. She has the capacity to go two days without sleep. 5. quality or state of being susceptible to a given treatment or action: Steel has a high capacity to withstand pressure. 6. position; function; role: He served in the capacity of legal adviser. 7. legal qualification.
8. Elect. a. capacitance.
b. maximum possible output.
—adj. reaching maximum capacity: a capacity audience; a capacity crowd.