That definition of cross-platform is a bit too narrow for my taste. I think a more reasonable definition of "cross-platform" would be "covers 2 or more roughly

That definition of cross-platform is a bit too narrow for my taste. I think a more reasonable definition of "cross-platform" would be "covers 2 or more roughly equal platforms". I mean no-one expects an app developed for a windows workstation to run (and be usable) on an andriod phone, even if it used a cross platform framework. But most would expect to be able to run it on linux or mac.