GAIA (gā′ə, gī′ə):

1) n. Greek Mythology: The goddess of the earth, who bore and married Uranus and became the mother of the Titans and the Cyclopes (The American Heritage® Dictionary of the English Language);

2) a complex entity involving the Earth's biosphere, atmosphere, oceans, and soil; the totality constituting a feedback or cybernetic system which seeks an optimal physical and chemical environment for life on this planet (Dr. James Lovelock. Gaia: A new look at life on Earth, 1979).

GAIA Hypothesis:

an ecological hypothesis proposing that the biosphere and the physical components of the Earth (atmosphere, cryosphere, hydrosphere and lithosphere) are coupled to form a complex interacting system. This coordinated system of living organisms maintains the climatic and biogeochemical conditions on Earth in a preferred homeostasis. This system is regarded as a single organism.