1. A metaphor for the holistic study of media use with particular reference to context, and especially the interrelationships of a medium or tool with its users' tasks, roles, attitudes, and practices; in contrast to the reductionism of media determinism.
2. The concept that the functional relationships of different types of media to each other (and the ways we use them) are continually shifted by the introduction of new media.
3. The notion of media as environments associated with McLuhan and Neil Postman, who claim that we unconsciously adapt to different media much as animals adapt to different habitats (see also media environments; medium theory; compare semiosphere).
4. Loosely, a synonym for media culture.
http://www.media-ecology.org/media_ecology/index.html What is media ecology?