What part of an aircraft is the empennage

Tail or tail assembly
The empennage (/ˌɑːmpᵻˈnɑːʒ/ or /ˈɛmpᵻnɪdʒ/), also known as the tail or tail assembly, of most aircraft gives stability to the aircraft, in a similar way to the feathers on an arrow; the term derives from the French for this.

Most aircraft feature an empennage incorporating vertical and horizontal stabilising surfaces which stabilise the flight dynamics of yaw and pitch, as well as housing control surfaces.

In spite of effective control surfaces, many early aircraft that lacked a stabilising empennage were virtually unflyable. Even so-called "tailless aircraft" usually have a tail fin (vertical stabiliser). Heavier-than-air aircraft without any kind of empennage (such as the McDonnell Douglas X-36) are rare.

Read more...https://en.wikipedia.org/wiki/Empennage