Technically, clouds and "clouds" are also molecular patterns.

For some definition of cloud. You also have on premises cloud. When Amazon runs their e-commerce site on AWS, are they running it on someone else's computer or not in cloud? (putting aside some tax-wise separation of individual Amazon subsidiaries)

On the other hand there are still providers that will rent you an server in their DC, but you don't get any API or anything else. At best they'll plug in HDDs that you sent them. This server hosting existed before "cloud" was a thing and it continues to exist.

I'd say that more accurate definition of cloud would be "someone else's computer with an API that customer can access". And if I'm really strict about that definition I'd drop entire first part, because it's the API that matters - computer might as well be yours.

Source: I've been on both sides of cloud from the very beginning.

again, while true that description is neither complete nor distinguished. It would get maybe 1 out of four possible points in a high school exam.

Not helpful for most things.