Plain English Meaning

A combined system that figures out how the airplane should be flown to follow a chosen path, then either shows the pilot what to do or flies the airplane itself.

Full Definition

An integrated avionics system combining two functions: a flight director, which computes and displays the pitch and bank steering commands needed to fly a selected flight path, and an autopilot, which can automatically move the flight controls to follow those same commands. The pilot selects the desired modes (such as heading, altitude, navigation tracking, or approach), and the system either shows the pilot how to fly them (flight director only) or flies them directly (autopilot engaged).