Piling means stacking things on top of each other, often messily or in growing amounts. When your dirty laundry keeps piling up in the corner of your room, clothes heap higher and higher. When snow keeps piling on the sidewalk during a blizzard, it accumulates in deeper and deeper layers.

The word captures both the action and the result. You might start piling books on your desk one at a time, but eventually you've created a precarious tower. Teachers often see homework assignments piling up on their desks, waiting to be graded. Football players pile on top of each other after a fumble, creating what announcers call a pile-up.

Piling suggests things are accumulating faster than they're being dealt with, or that they're being stacked somewhat carelessly. When responsibilities keep piling on, they're adding up quickly. When friends pile into a car, they're climbing in enthusiastically and crowding together without worrying about neat arrangement.

The word also has a technical meaning in construction: pilings (or piles) are long poles driven deep into the ground to support buildings, bridges, or docks, especially over water or soft soil.