English to English
1. a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena
theories can incorporate facts and laws and tested hypotheses|true in fact and theory
2. a tentative insight into the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena
a scientific hypothesis that survives experimental testing becomes a scientific theory|he proposed a fresh theory of alkalis that later was accepted in chemical practices
3. a belief that can guide behavior
the architect has a theory that more is less|they killed him on the theory that dead men tell no tales
4. A doctrine, or scheme of things, which terminates in speculation or contemplation, without a view to practice; hypothesis; speculation.