Plain English Meaning
How well a multiengine airplane can still climb after one engine quits. It depends on the airplane's weight, the air temperature, the altitude, how the airplane is configured, and how precisely the pilot flies it.
Full Definition
The climb capability of a multiengine airplane when one engine has failed or been intentionally shut down and the remaining engine (or engines) is producing takeoff or maximum continuous power. It is expressed as a rate of climb (feet per minute) or a climb gradient (feet gained per nautical mile) at a specified weight, altitude, temperature, and configuration, with the failed engine's propeller feathered and the airplane flown at the published best single-engine climb speed ().