1. (用于击碎岩石和混凝土的)大锤
A sledgehammer is a large, heavy hammer with a long handle, used for breaking up rocks and concrete.

2. 杀鸡用牛刀
If you say that someone is using a sledgehammer to crack a nut, you mean that they are using stronger measures than are really necessary to solve a problem.

1. a heavy long-handled hammer used to drive stakes or wedges

Synonym: maulsledge