I have a small business enterprise. I, like others, had always thought of an enterprise as being a huge company.
However, the definition of "enterprise" states that it may be bold or require energy. I can tell you from experience that any business, big or small, fits that aspect of the definition!
Now that I have some experience as a business owner, I think that any business is a huge undertaking. And I think that to call it an enterprise is quite fitting.