Meaning of primordial soup

primor'dial soup'

Pronunciation: [key]
— Biol. Biol.
  1. the seas and atmosphere as they existed on earth before the existence of life, consisting primarily of an oxygen-free gaseous mixture containing chiefly water, hydrogen, methane, ammonia, and carbon dioxide.
  2. a laboratory preparation containing the substances believed to have composed primordial soup, and used in experiments seeking to understand the origin of life.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.