chain reaction

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A series of events in which each induces or influences the next.
• noun Physics A multistage nuclear reaction, especially a self-sustaining series of fissions in which the release of neutrons from the splitting of one atom leads to the splitting of others.
• noun Chemistry A series of reactions in which one product of a reacting set is a reactant in the following set.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun physics A nuclear reaction in which particles produced by the fission of one atom trigger fissions of other atoms.
• noun idiomatic A series of events, each one causing the next.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a self-sustaining nuclear reaction; a series of nuclear fissions in which neutrons released by splitting one atom leads to the splitting of others
• noun a series of chemical reactions in which the product of one is a reactant in the next