from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. Biology A close, prolonged association between two or more different organisms of different species that may, but does not necessarily, benefit each member.
  • n. A relationship of mutual benefit or dependence.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A relationship of mutual benefit.
  • n. A close, prolonged association between two or more organisms of different species, regardless of benefit to the members.
  • n. The state of people living together in community.

from the GNU version of the Collaborative International Dictionary of English

  • n. The living together in more or less imitative association or even close union of two dissimilar organisms. In a broad sense the term includes parasitism, or antagonistic symbiosis or antipathetic symbiosis, in which the association is disadvantageous or destructive to one of the organisms, but ordinarily it is used of cases where the association is advantageous, or often necessary, to one or both, and not harmful to either. When there is bodily union (in extreme cases so close that the two form practically a single body, as in the union of algæ and fungi to form lichens, and in the inclusion of algæ in radiolarians) it is called conjunctive symbiosis; if there is no actual union of the organisms (as in the association of ants with myrmecophytes), disjunctive symbiosis.

from The Century Dictionary and Cyclopedia

  • n. Union for life of certain organisms, each of which is necessary to the other; an intimate vital consociation, or kind of consortism, differing in the degree and nature of the connection from inquilinity and parasitism, as in the case of the fungus and alga which together make up the so-called lichen, or of the fungus Mycorrhiza and various Cupuliferæ. See Lichenes, Mycorrhiza. Also called commensalism.

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

  • n. the relation between two different species of organisms that are interdependent; each gains benefits from the other


from The American Heritage® Dictionary of the English Language, 4th Edition

Greek sumbiōsis, companionship, from sumbioun, to live together, from sumbios, living together : sun-, syn- + bios, life; see gwei- in Indo-European roots.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Ancient Greek συμβίωσις (sumbiōsis, "living together").


  • I often wonder what kind of science career she might have had, had she been born later -- did you know she was the first to identify lichen as two organisms living in symbiosis?

    The Cottage Tales of Beatrix Potter

  • They may be said to live in symbiosis with their environment.

    The Nobel Prize in Chemistry 1977 - Presentation Speech

  • Rather, they recognize the inherent conflicts that arise among the demands of the various stakeholders as well as the need to endeavor to attain "symbiosis" - that is, interdependence and mutual benefit-among the various stakeholder groups.

    Recently Uploaded Slideshows

  • The domestic symbiosis is tripartite – Neo-Cons, Born Again Zionists, Corporate Fascists.

    Ledeen and Chinese ‘Fascism’ « Blog

  • But back in the here and now, not only am I finding it very hard to come up with a feminism that sits comfortably with being transsexual, but I’m also starting to wonder if such a symbiosis is even possible.

    Don’t panic

  • And before I read this book I knew nothing about wild mushrooms, how they live in symbiosis with trees and can’t be cultivated.

    » Omnivore’s Dilemma

  • The relationship is intuitive, connecting the two in symbiosis.

    Spread ArtCulture: Patricia Piccinini's World of Creatures Great & Small

  • There's the winter scenes, and the magical and useful animal companions with whom the protag lives in symbiosis.

    reading Update

  • Building on the notion of symbiosis in nature, highly interconnected industrial networks using wastes as process inputs (industrial symbioses) should more closely mimic the parsimony of closed-loop natural systems.

    Industrial ecology

  • In that story, I frequently referred to one or the other of the partners in the biological relation called symbiosis as a symbiote.

    Through The Eye Of A Needle


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  • Bah, wikipedia. The work of ideologues and heathens!

    Actually that is interesting. Thank you, signor.

    August 9, 2008

  • As Wikipedia well explains, symbiosis is now generally used in a wider sense... Symbiosis sensu stricto can be more narrowly called mutualism.

    August 9, 2008

  • Isn't reciprocity the essence of symbiosis? Parasitic and symbiotic relationships are mutually exclusive.

    August 9, 2008

  • Parasitic relationships are a kind of symbiosis, too - a kind with no reciprocity.

    August 9, 2008

  • Not necessarily, no. In fact if you have two organisms each consuming the other, it wouldn't be symbiotic because one or both would die as a result. But you might be thinking, for example, of those little fish that eat the parasites off sharks. The little fish get fed, and the shark gets rid of its parasites.

    August 9, 2008

  • Isn't it a feeding off of one another?

    August 9, 2008

  • No, seriously, jmp! The word symbiosis, for many reasons, is now used again in its literal meaning of "living together".

    I would not insist, but this is a field I know quite well - and I love. :-)

    June 22, 2008

  • No, I think it's the opposite. Symbiosis is the case where the whole is greater than the sum of its parts.

    June 22, 2008

  • Well spotted. Symbiotic has a more correct definition, while this one is more naïve and old-fashioned.

    June 22, 2008

  • Why is the head definition for this word the opposite of the head definition for its adjective, symbiotic?

    June 22, 2008