Plain English Meaning

Instead of flying a printed departure route, the controller watches you on radar after takeoff and tells you which headings and altitudes to fly until you're pointed toward your route.

Full Definition

A departure procedure in which Air Traffic Control uses radar to provide navigational guidance and vectors to the pilot from shortly after takeoff until the aircraft is established on its filed route or assigned course. The pilot follows ATC headings and altitudes rather than a published departure procedure.