1) N-VAR Someone's environment is all the circumstances, people, things, and events around them that influence their life.

Pupils in our schools are taught in a safe, secure environment...

The moral characters of men are formed not by heredity but by environment...

The twins were separated at birth and brought up in entirely different environments.

2) N-COUNT: usu sing, with supp Your environment consists of the particular natural surroundings in which you live or exist, considered in relation to their physical characteristics or weather conditions.

If our environment cools, then messages from the skin alert the body's thermostat.

...the maintenance of a safe environment for marine mammals.

3) N-SING: the N The environment is the natural world of land, sea, air, plants, and animals.

...Conservative spokesman on the environment.

...persuading people to respect the environment.

English dictionary. 2008.