sym·bi·o·sis (s?m?b?-??s?s, -b?-)n. pl. sym·bi·o·ses (-s?z) 1. Biology 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.[Greek sumbi?sis, companionship, from sumbioun, to live together, from sumbios, living together : sun-, syn- + bios, life; see gwei- in Indo-European roots.]sym?bi·ot?ic (-?t??k), sym?bi·ot?i·cal (-?-k?l) adj.sym?bi·ot?i·cal·ly adv.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.symbiosis (?s?mb????s?s; ?s?mba????s?s) n1. (Biology) a close and usually obligatory association of two organisms of different species that live together, often to their mutual benefit2. (Sociology) a similar relationship between interdependent persons or groups[C19: via New Latin from Greek: a living together; see symbiont] ?symbi?otic, ?symbi?otical adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014sym?bi?o?sis (?s?m bi?o? s?s, -ba?-) n., pl. -ses (-s?z). 1. a. the living together of two dissimilar organisms, as in mutualism, commensalism, or parasitism. b. (formerly) mutualism. 2. any interdependent or mutually beneficial relationship between two persons, groups, etc. [1615?25;