In my opinion all words are subjective, and their understood meaning is basically a generally accepted shared subjective definition. So it depends on how you define property..

I define a property as: a scarce tangible entity, corporeal or incorporeal, of which the access to and control of has been restricted and limited

The important part of my definition is scarcity. I do not regard entities that aren't scarce as property for example such as information that can be easily and cheaply perfectly copied without causing a loss what so ever to the original medium it was carried by.



So given my definition in Bitcoin only a Bitcoin transactions(more precisely the unspent outputs as was alluded to above) fits it. It is a tangible incorporeal and scarce entity that I restricted and limited the use of by keeping my private keys secret. When someone steals my bitcoins what they really stole is the irreversible and non double spendable and therefor scarce transaction that can be made with the private key and that I have restricted and limited the use of.

So they may copy my private key which is just information which isn't really a property and that alone does nothing to me, I mean I don't experience a loss what so ever. But if they then use this private key to steal my scarce transaction then that's when the loss to me actually happens and they stole my property.

I mean if you really think about it the same happens with say a gold coin that you own. Someone may learn where you keep it and how to turn of your security measures in order to gain access but they haven't inflicted a loss on you with the access to this information alone, it's when they use this information to take possession of the scarce entity that you experience the loss i.e. theft.