Is it a metaphor or a theory?

I was thinking of something and wanted to label it as a "metaphor", but something didn't seem quite right. So, I checked the dictionary entry for "metaphor", and didn't find what I had expected. I had thought that a metaphor was synonymous with a model or a paradigm, but in fact it's simply a "figure of speech", a form of analogy.

A "window" is a metaphor on a computer not because it's a model or approach, but simply because it is analogous to the function of a window in the real-world. Ditto for folders and files. Strictly speaking, a "database" is not a metaphor (on a computer) since it does not have any obvious "figure of speech" analog in the real world.

There is a second meaning in the dictinary, which is that a metaphor can be a symbol that represents an object, activity, or idea. But that's still quite a distance from model or paradigm. In fact, I'm not interested in a mere symbol or name at all, but wanting an umbrella term that technically and descriptively covers the totality of the concept that I'm thinking of. Maybe I simply need to bite the bullet (which is a metaphor) and call my conceptual idea a "theory".

On the other hand, maybe the dictionary is still a few years behind and the general parlance of a metaphor as a model or paradigm will eventually get swept up by the dragnet of the dictionary editors. It would seem "safe" to use metaphor as a synonym for model or pattern or paradigm, but I'm not fan or "re-purposing" normal English words that already have a rather clear meaning.