noun / adjective
rear
REER/rˈɪr/
The back part of something or a position toward it.
The car's rear includes the back window, red taillights, and bumper.

Etymology
The 'behind' element in a term for a rear guard came to name the back part more generally. Some early examples may instead be shortened forms of arrear.
In context
the primary piston assembly has a seal located in a machine Groove at the front and a secondary cup or O ring at the rear
More examples
- We store extra chairs at the rear of the room.
- A red light flashes on the rear of the bike.
- He slips on the ice and lands on his rear.
Forms
rear · rears
rearward adjective — Located or directed toward the back.
Similar words
- back
- More general; also names the surface opposite the front.
- hindmost
- Specifically identifies the farthest back in a group or line.