noun
- Also called physiological atmosphere. the part of the atmosphere in which it is possible to breathe normally without aid: the portion of the troposphere from sea level to an altitude of about 13,000 feet (4000 meters).
- Ecology. the planetary ecosystem, including all the earth’s living organisms and their physical environment; biosphere.
noun
- the planetary ecosystem, consisting of all living organisms and their environment
1953, the region around a star where conditions allow life-bearing planets to exist; see eco- + sphere. Apparently coined by German-born U.S. physician and space medicine pioneer Hubertus Strughold (1898-1986).
- The regions of the Earth that are capable of supporting life, together with the ecosystems they contain; the biosphere.