Most people thinks that a theory means the same thing in science as it does in the vernacular.
This is an outright falsehood. Linus Pauling was a Nobel laurate in chemistry and is without a doubt one of the greatest chemists of the Twentieth Century, if not all time. For example there is a law of constancy of the angles between the faces of crystals. This law states that whenever the angles between corresponding faces of various crystals of a pure substance are measured they are found to have the same value, whether the crystal is a small one or a large one. It does not explain this fact.