A compactor is a machine that crushes or presses things together to make them smaller and take up less space. The most common type is a trash compactor, which squashes garbage so that more fits in each bag or dumpster. Instead of a trash can overflowing with bulky boxes and bottles, a compactor can compress it all into a dense block.

Large construction sites use soil compactors (sometimes called rollers) to pack down dirt and gravel, making the ground solid and stable before building. These heavy machines have huge steel drums or wheels that roll over the earth repeatedly, pressing out air pockets and creating a firm foundation for roads or buildings.

When something is compacted, it becomes denser and more tightly packed. You might see this word used metaphorically too: a writer might say they compacted their essay, meaning they condensed it to make it shorter and more focused without losing important ideas.