rear 1 
(rîr)
(rîr)n.
1. A hind part.
2. The point or area farthest from the front: the rear of the hall.
3. The part of a military deployment usually farthest from the fighting front.
4. Informal The buttocks.
adj.
Of, at, or located in the rear.
[Middle English rere, rear of an army, short for rerewarde, rear guard; see REARWARD2.]