Plain English Meaning

The slowest speed at which a pilot can still keep a twin-engine airplane flying straight when one engine suddenly fails for real, with the other engine still pulling hard. It is the in-the-moment version of the published minimum control speed.

Full Definition

The minimum airspeed at which directional control of a multi-engine airplane can be maintained during the sudden, real-world failure of one engine, where the working engine is producing significant power and the airplane is responding to the abrupt yawing and rolling forces created by that failure. Unlike the static VMC value certified by the manufacturer (which is determined under specific, controlled test conditions), dynamic VMC reflects what actually happens to the airplane in when an engine quits unexpectedly and must react in real time.