I get a kick out of various pieces of software being described as "enterprise" software. I've seen lots of commercial software as well Zope and Plone referred to in this way, mostly by magazine reviewers. The word "enterprise" is usually used as some sort of vague apology for the state of the software's documentation: "You wouldn't really want to use Zope for casual websites, it's an enterprise solution."

If you read this literally, "enterprise" might mean "somewhat underdocumented" and "a bit difficult to understand". Zope can definitely be used in an enterprise, and it's pretty stable nowadays, and I'm constantly amazed seeing "normal" people dig into its internals to gain deep understanding lately in a way that they just didn't two or three years ago. But it shouldn't be called an "enterprise solution" because it can be hard to understand. There's no reason that "enterprise" software can't be used casually. In fact, the very definition of "enterprise" by people who really care about it (the corner-office types) is "I won't get in trouble using it", which translates to tech people as "well-understood and stable". And well-understood and stable software can often be used casually. I'd almost say that most "true" enterprise software (say, Apache stable releases) is just so invisible that nobody even thinks about the fact that it might not work because it has such high quality in both its code and documentation. "True" enterprise software "just works".

I actually blame large commercial software vendors for this misunderstanding. They sold huge steaming piles of underdocumented code that needs to be customized and implemented by special consultants (SAP, PeopleSoft, and so forth) and apologized for that by calling it "enterprise". Brilliant marketing tactic, but it doesn't make much clearer for the corner office types and the magazine reviewers.