capacity (n.) Look up capacity at Dictionary.com
early 15c., from Middle French capacité "ability to hold" (15c.), from Latin capacitatem (nominative capacitas) "breadth, capacity, capability of holding much," noun of state from capax (genitive capacis) "able to hold much," from capere "to take," from PIE root *kap- "to grasp" (see capable). Meaning "largest audience a place can hold" is 1908.