1. （汽车前后的）保险杠
Bumpers are bars at the front and back of a vehicle which protect it if it bumps into something.

2. 丰收的；丰盛的
A bumper crop or harvest is one that is larger than usual.

3. 巨大的；大号的
If you say that something is bumper size, you mean that it is very large.

1. a mechanical device consisting of bars at either end of a vehicle to absorb shock and prevent serious damage

2. a glass filled to the brim (especially as a toast)

e.g. we quaffed a bumper of ale