am·​pac·​i·​ty ˌam-ˈpa-sə-tē How to pronounce ampacity (audio)
plural ampacities
: the maximum amount of current that a wire or cable can safely carry
The longer the brush, the longer the life; therefore, when a brush is operating at 40 to 50 percent below the maximum current capacity (ampacity) per inch and has an extra long length, the motor can have a very long life.A. N. Tsergas

Word History


blend of amp, abbreviation for amperage, and capacity entry 1

First Known Use

1953, in the meaning defined above

Time Traveler
The first known use of ampacity was in 1953

Dictionary Entries Near ampacity

Cite this Entry

“Ampacity.” Dictionary, Merriam-Webster, Accessed 26 Sep. 2023.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!