pile 2 
(p
īl)
n.1. A heavy post of timber, concrete, or steel, driven into the earth as a foundation or support for a structure.
2. Heraldry A wedge-shaped charge pointing downward.
3. A Roman javelin.
tr.v. piled,
pil·ing,
piles 1. To drive piles into.
2. To support with piles.
[Middle English, from Old English pīl, shaft, stake, from Latin pīlum, spear, pestle.]

pile2