Well, it's a lot more than that. Science is the best way we have to understand the natural world. It's not perfect, being a human endeavor, but it's self-correcting and, given enough time, leads to better understanding.
In science, the word "theory" means a concept that is so well-supported by evidence that it's generally accepted as "truth"... at least in the scientific community. A theory starts as a "hypothesis", which may be not much more than an observation or educated guess. Then the hypothesis is tested, attempting to show that it's wrong; in other words to "falsify" it. If this happens, the scientist goes back to the drawing board and generates another hypothesis. When the hypothesis has been tested enough by multiple investigators, and becomes useful for making predictions, it attains the status of a theory.
Examples of theories include Germ Theory of Disease, Evolution, Continental Drift. These have stood the test of time and many challenges, but they *could* be falsified... whoever did this would instantly win the Nobel Prize!