Definition (1):
The angle of departure is the steepest angle of the inclined roadway from which a vehicle can be driven onto a level roadway without the vehicle's rear overhang making contact with the inclined surface.
Definition (2):
According to merriam-webster.com/dictionary, angle of departure refers to “the vertical angle between the line of departure of a projectile and the line of site of the gun.”
Definition (3):
Approach angle is the maximum ramp angle onto which a car or any other vehicle is able to climb from a horizontal plane without any interference. It is the angle between the land and the line running between the front tire and the vehicle’s lowest hanging part at the front overhang. Departure angle or angle of departure is its counterpart at the vehicle’s rear- the maximum angle of a ramp from which the vehicle is able to descend without damage. These angles are called ramp angles too. These angles are indicators of the vehicle’s off-road ability. They show how steep hindrances or obstacles like logs or rocks, the vehicle is able to negotiate as per its shape of the body alone.