Exactly. It isn't functional. It doesn't use functions. It uses message passing instead. That is exactly why the term "object-oriented" was originally coined for Smalltalk. It didn't fit within the use of "imperative" and "functional" that preceded it.

> But that kinda ruins the common ground thesis.

That is the thesis: That Smalltalk is neither imperative nor functional. That is why it was given its own category. Maybe you've already forgotten, but I will remind that it was Smalltalk's creator that invented the term "object-oriented" for Smalltalk. Smalltalk being considered something different is the only reason for why "object-oriented" exists in the lexicon.

Erlang is the language that challenges the common ground thesis: It has both functions with encapsulation and message passing with encapsulation. However, I think that is easily resolved by accepting that it is both functional and object-oriented. That is what Joe Armstrong himself settled on and I think we can too.

> What I prefer is looking at it as it's used.

And when you look you'll soon find out that there is no commonality here. Everyone has their own vastly different definition. Just look at how many different definitions we got in this thread alone.

> No one would agree that a cucumber is a fruit.

Actually, absent of context defining whether you are referring to culinary or botanical, many actually do think of a cucumber as a fruit. The whole "did you know a tomato is actually a fruit?" is something that made the big leagues in the popular culture. However, your general point is sound: The definitions used are consistent across most people. That is not the case for object-oriented, though. Again, everyone, their brother, and pjmlp have their own thoughts and ideas about what it means. Looking at use isn't going to settle on a useful definition.

Realistically, if you want to effectively use "object-oriented" in your communication, you are going to have to explicitly define it each time.