"Ecology - is the pattern of relations of plants, animals, and people to each other and to their surrounding.
The aim of ecology is studying the structure of population, and the attitude towards populations of other species, studying inter-dependences of all populations that live on the fixed area and make know inluences which are produced by populations and inanimate surroundings.

"1. The branch of biology dealing with the relations of organisms to one another and to their physical surroundings."
"2. (in full human ecology) the study of the interaction of people with their environment."

ECOLOGY - Gk oikos - house, and logos - word, science

1. and 2. from Concise Oxford Dictionary