e·col·o·gy (?-k?l??-j?)n. pl. e·col·o·gies 1. a. The science of the relationships between organisms and their environments.b. The relationship between organisms and their environment.2. See human ecology.[German Ökologie : Greek oikos, house; see weik- in Indo-European roots + German -logie, study (from Greek -logi?, -logy).]ec?o·log?i·cal (?k??-l?j??-k?l, ??k?-), ec?o·log?ic (-?k) adj.ec?o·log?i·cal·ly adv.e·col?o·gist n.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.ecology (??k?l?d??) n1. (Environmental Science) the study of the relationships between living organisms and their environment2. (Environmental Science) the set of relationships of a particular organism with its environment3. (Sociology) the study of the relationships between human groups and their physical environment Also called (for senses 1, 2): bionomics [C19: from German Ökologie, from Greek oikos house (hence, environment)] e?cologist nCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014e?col?o?gy (??k?l ? d?i) n. 1. the branch of biology dealing with the relations and interactions between organisms and their environment. 2. the set of relationships existing between organisms and their environment. 3. Also called human ecology. the branch of sociology concerned with the spacing and interdependence of people and institutions. 4. the advocacy of protection of the air, water, and other natural resources from pollution or its effects; environmentalism. [1870?75; earlier oecology