A steamroller is a large, heavy machine with massive metal rollers used to flatten and smooth roads, parking lots, and other paved surfaces. Picture a huge cylinder, sometimes 10 feet wide, slowly rolling forward with tremendous weight and power. The machine got its name because early versions in the 1800s were powered by steam engines, though modern steamrollers use diesel or gasoline.

The key thing about a steamroller is its unstoppable quality. It moves slowly but with such enormous weight and force that it flattens everything in its path. A single steamroller can weigh as much as 20 cars, pressing down with tons of pressure to compress gravel, asphalt, or dirt into a smooth, solid surface.

Because of this crushing power, people use steamroller as a verb to describe overwhelming force or dominance. When one basketball team absolutely crushes another, winning 98 to 45, you might say they steamrollered their opponents. If someone steamrollers a discussion, they push their opinion forward so forcefully that nobody else gets a chance to speak. A student might complain that the class bully tries to steamroller everyone into doing what he wants.

The image is always the same: massive, slow, unstoppable force that flattens everything in its path.