defination of "Theory" in different categories and methodologies please.thanks?

Answer 1

The word theory has a number of distinct meanings in different fields of knowledge, depending on their methodologies and the context of discussion.

In science, a theory is a mathematical or logical explanation, or a testable model of the manner of interaction of a set of natural phenomena, capable of predicting future occurrences or observations of the same kind, and capable of being tested through experiment or otherwise falsified through empirical observation. It follows from this that for scientists "theory" and "fact" do not necessarily stand in opposition. For example, it is a fact that an apple dropped on earth has been observed to fall towards the center of the planet, and the theories commonly used to describe and explain this behaviour are Newton's theory of universal gravitation (see also gravitation), and general relativity.

In common usage, the word theory is often used to signify a conjecture, an opinion, or a speculation. In this usage, a theory is not necessarily based on facts; in other words, it is not required to be consistent with true descriptions of reality. This usage of theory leads to the common incorrect statement "It's not a fact, it's only a theory." True descriptions of reality are more reflectively understood as statements which would be true independently of what people think about them. In this usage, the word is synonymous with hypothesis.

Answer 2

http://en.wikipedia.org/wiki/Theory

It is description identified as a model or map for knowing a thing and what it may do. Such descriptions detail a hypothetical context wherein an unsensable or insensible system or process is described, hence the necessity for the word 'theory', but not all theories have an insensible part to their description, i.e. a theory may describe a completely sensible thing, a thing completely detectable in the senses and rightly subject to investigation, e.g. a rock on the road.