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[sim-bee-oh-sis, -bahy-] /ˌsɪm biˈoʊ sɪs, -baɪ-/
noun, plural symbioses
[sim-bee-oh-seez, -bahy-] /ˌsɪm biˈoʊ siz, -baɪ-/ (Show IPA)
  1. the living together of two dissimilar organisms, as in mutualism, commensalism, amensalism, or parasitism.
  2. (formerly) mutualism (def 1).
Psychiatry. a relationship between two people in which each person is dependent upon and receives reinforcement, whether beneficial or detrimental, from the other.
Psychoanalysis. the relationship between an infant and its mother in which the infant is dependent on the mother both physically and emotionally.
any interdependent or mutually beneficial relationship between two persons, groups, etc.
1615-25; < Greek symbíōsis, equivalent to sym- sym- + biō (variant stem of bioûn to live) + -sis -sis
Related forms
[sim-bee-ot-ik, -bahy-] /ˌsɪm biˈɒt ɪk, -baɪ-/ (Show IPA),
symbiotical, adjective


[sim-bee-ot-ik, -bahy-] /ˌsɪm biˈɒt ɪk, -baɪ-/
living in symbiosis, or having an interdependent relationship:
Many people feel the relationship between humans and dogs is symbiotic.
Sometimes, symbiotical.
Related forms
symbiotically, adverb
nonsymbiotic, adjective
nonsymbiotical, adjective
nonsymbiotically, adverb Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for symbiotical


/ˌsɪmbɪˈəʊsɪs; ˌsɪmbaɪˈəʊsɪs/
a close and usually obligatory association of two organisms of different species that live together, often to their mutual benefit
a similar relationship between interdependent persons or groups
Derived Forms
symbiotic, (rare) symbiotical, adjective
Word Origin
C19: via New Latin from Greek: a living together; see symbiont
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for symbiotical



1877, as a biological term, "mutually beneficial association of two different organisms," from Modern Latin, from Greek symbiosis "a living together," from symbioun "live together," from symbios "(one) living together (with another), partner," from syn- "together" (see syn-) + bios "life" (see bio-). Given a wider (non-biological) sense by 1921. An earlier sense of "communal or social life" is found in 1620s.



1882, in biology, from symbiosis. Of human activities, from 1951.

Online Etymology Dictionary, © 2010 Douglas Harper
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symbiotical in Medicine

symbiosis sym·bi·o·sis (sĭm'bē-ō'sĭs, -bī-)
n. pl. sym·bi·o·ses (-sēz)

  1. A close, prolonged association between two or more different organisms of different species that may, but does not necessarily, benefit each member.

  2. A relationship of mutual benefit or dependence.

symbiotic sym·bi·ot·ic (sĭm'bē-ŏt'ĭk, -bī-)
Of, resembling, or relating to symbiosis.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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symbiotical in Science
The close association between two or more organisms of different species, often but not necessarily benefiting each member. The association of algae and fungi in lichens and of bacteria living in the intestines or on the skin of animals are forms of symbiosis. Some scientists believe that many multicellular organisms evolved from symbiotic relationships between unicellular ones and that the DNA-containing organelles within certain eukaryotic cells (such as mitochondria and chloroplasts) are the product of symbiotic relationships in which the participants became interdependent. There are four forms of symbiosis: amensalism, commensalism, mutualism, and parasitism.

symbiotic adjective
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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symbiotical in Culture
symbiosis [(sim-bee-oh-sis, sim-beye-oh-sis)]

The process by which two organisms live together, usually to their mutual benefit. An example of a symbiotic pair are cows and the bacteria that live in their digestive tracts, enabling them to digest cellulose in grass.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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