Then it is not possible to 'steal' an idea? Afaik 'to steal'is simply to take without permission. If the thing is abstract, then you might not have deprived the original owner of that thing. If the thing is a physical object, then the implication is tou now have physical possession (in which case your definition seemingly holds)
edit/addendum: considering this a bit more - the extent to which the original party is deprived of the stolen thing is pertinent for awarding damages. For example, imagine a small entity stealing from a large one, like a small creator steals dungeon and dragons rules. That doesn't deprive Hasbro of DnD, but it is still theft (we're assuming a verbatim copy here lifted directly from DnD books)
The example that I was pondering were shows in russia that were almost literally "the sampsons." Did that stop the Simpson's from airing in the US, its primary market? No, but it was still theft, something was taken without permission.