Plain English Meaning
It is the lowest height above the ground at which a multi-engine airplane can lose one engine and still be flown safely while the pilot sorts the situation out.
Full Definition
In multi-engine airplane operations, the minimum altitude above the ground at which a pilot can safely maneuver the airplane following the failure of one engine, allowing time and height to control the airplane, identify the failure, configure for single-engine flight, and either continue flight or execute a controlled landing.
Context Anchor
You will see this term in multiengine takeoff planning, especially when deciding what to do if an engine fails shortly after .