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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.
symbiosis sym·bi·o·sis (sĭm'bē-ō'sĭs, -bī-)
n. pl. sym·bi·o·ses (-sēz)
A close, prolonged association between two or more different organisms of different species that may, but does not necessarily, benefit each member.
A relationship of mutual benefit or dependence.
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.