backedge

例句：

1. 1.The car's back edge is sharper than the front.
   这辆车的后部比前部更锐利。
2. 2.The back edge of the table is smooth.
   桌子的背面很平滑。
3. 3. He leaned back against the wall, feeling the back edge of his chair.
   他靠在墙上，感觉到椅子的背面。