1. A vertical wood, metal, or concrete support or column for a building or other structure that is driven into the ground.
2. A long stake or pointed pole which is pushed into the ground to support something; such as, a building.
3. A collection or group of objects that are heaped, stacked, or laid on top of each other.
4. Etymology: "a pillar, a pier of a bridge", from Latin pila, "a stone barrier"; from Latin "pier, harbor wall of stones" then to "something that is heaped up".

To put something in a stack: "Mary piled the books high on the floor and her clothes were piling up on the chair."

"Sam, what do you plan to do with those newspapers after you pile them up?"