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

  • noun A state of equilibrium, as in an organism or cell, maintained by self-regulating processes.

from the GNU version of the Collaborative International Dictionary of English.

  • noun The ability and tendency of certain systems to maintain a relatively constant internal state in spite of changes in external conditions; this ability is achieved by the presence of feedback mechanisms which can adjust the state of the system to compensate for changes in the state caused by the external environment. It is exemplified in homeothermal biological systems, such as animals which maintain relatively constant blood temperature and composition in spite of variations in external temperature or the composition of the food ingested.

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

  • noun physiology The ability of a system or living organism to adjust its internal environment to maintain a stable equilibrium; such as the ability of warm-blooded animals to maintain a constant temperature.
  • noun Such a dynamic equilibrium or balance.

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

  • noun (physiology) metabolic equilibrium actively maintained by several complex biological mechanisms that operate via the autonomic nervous system to offset disrupting changes


from Wiktionary, Creative Commons Attribution/Share-Alike License

Coined from Ancient Greek ὅμος (hómos, "similar") + ιστημι (histēmi, "standing still")/stasis (from στάσις) by Walter Bradford Cannon.


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  • "In the late nineteen-twenties, the physiologist Walter Cannon coined the term “homeostasis”—joining together the Greek homoios (similar) and stasis (stillness). The capacity to sustain internal constancy was an essential feature of an organism, he argued."

    -- "My Father’s Body, at Rest and in Motion" by Siddhartha Mukherjee (

    January 4, 2018