Meaning of big bang theory

big' bang' the"ory

Pronunciation: [key]
— Astron. Astron.
  1. a theory that deduces a cataclysmic birth of the universefrom the observed expansion of the universe, cosmic background radiation, abundance of the elements, and the laws of physics. Also calledCf.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.