Final answer:
A scientific theory is a well-supported explanation of observations, while the common definition of theory refers to a guess or speculation. Scientific theories are comprehensive explanations based on substantial evidence, while the common definition of theory implies a simple guess.
Step-by-step explanation:
A scientific theory is a well-supported explanation of observations, while the common, everyday meaning of the word theory refers to a guess or speculation. In science, a theory is not just a simple guess, but rather a comprehensive explanation of an important feature of nature that is supported by facts gathered over time. It is more like a fact than a guess because it is thoroughly tested and has substantial evidence behind it.