The study of the material universe or physical reality in order to understand it. This is done by making observations and collecting data about natural events and conditions, then organising and explaining them with hypotheses, theories, models, laws, and principles.

The organised body of knowledge about the material universe which can be verified or tested.

A particular branch of either the process of study or the body of knowledge, such as astronomy, biology, chemistry, geology, and physics.

(09 Oct 1997)