Definition of theme - Environment

Environment Is:

The surroundings of, and influences on, a particular item of interest.The natural world or ecosystem.All the elements over which a designer has no control and that affect a system or its inputs and outputs. A particular political or social setting, arena or condition. External conditions or surroundings, etc. especially those in which people live or work.Ecology the external surroundings in which a plant or animal lives, which tend to influence its development and behaviour

Source: http://en.wiktionary.org/wiki/environment

http://www.thefreedictionary.com/environment

Environment is the external conditions or surroundings that influences a particular item of interest. It is also the natural world or ecosystem. There are no control over all the elements of environment and that affects a system. It is a setting.