In ecology, it is the sum total of biological, chemical and physical factors in some circumscribed area. It really only exists because it is inhabited by an organism. For example, a field is an environment for a horse, its droppings the environment for beetles and their exoskeletons the environment for parasitic mites. Thus, the field compromises a series of overlapping environments. Ecologists use the term interchangeably with habitat or niche. In psychology, following Kurt Lewin (1890-1947), there is also a psychological environment, a selective representation of the physical environment and the way in the holder of that representation thinks it determines his or her behavior.
See Behavior genetics, Context (cultural), Ecological systems theory, Ecology, Environment of evolutionary adaptedness, Habitat (ecology), Niche (ecology)