The Collaborative International Dictionary of English v.0.48:
Pile \Pile\, n. [AS. p[imac]l arrow, stake, L. pilum javelin;
but cf. also L. pila pillar.]
1. A large stake, or piece of timber, pointed and driven into
the earth, as at the bottom of a river, or in a harbor
where the ground is soft, for the support of a building, a
pier, or other superstructure, or to form a cofferdam,
Note: Tubular iron piles are now much used.
2. [Cf. F. pile.] (Her.) One of the ordinaries or
subordinaries having the form of a wedge, usually placed
palewise, with the broadest end uppermost.
Pile bridge, a bridge of which the roadway is supported on
Pile cap, a beam resting upon and connecting the heads of
Pile driver, or Pile engine, an apparatus for driving
down piles, consisting usually of a high frame, with
suitable appliances for raising to a height (by animal or
steam power, the explosion of gunpowder, etc.) a heavy
mass of iron, which falls upon the pile.
Pile dwelling. See Lake dwelling, under Lake.
Pile plank (Hydraul. Eng.), a thick plank used as a pile in
sheet piling. See Sheet piling, under Piling.
Pneumatic pile. See under Pneumatic.
Screw pile, one with a screw at the lower end, and sunk by
rotation aided by pressure.