from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An early type of nuclear reactor whose core consisted of layers of graphite block interspersed with uranium, designed to create a sustained fission reaction.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. an early nuclear reactor fuelled by uranium and moderated with graphite
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a nuclear reactor that uses controlled nuclear fission to generate energy
atomic + Italian pila, battery (Wiktionary)
I'd looked into the heart of the uranium atomic pile through a heavily leaded glass-inspection port and seen the indescribable unearthly radiance of it, a nightmarish coalescence of green and violet and blue, the new "dreadful light" of mankind.