You are describing the difference between real property and personal property (chattels) not the difference between property and not-property. 
The best way to think about property is as a bundle of rights and obligations not as an actual object.
What you describe for real property isn't necessarily true in all cases either: Going through your points one by one:
Property doesn't have to be registered - In some jurisdictions transfers of ownership and ownership of real property does have to be registered. This type of system is known as a Torrens System and is used in Australia, New Zealand, Alberta, and British Columbia just off the top of my head.
Property doesn't have a term after which it expires:
Leasehold property, or life estates do have a time after which ownership expires.
Even freehold property is subject to escheat as well.
Some IPR aren't fully transferable, unlike property:
Hmm nothing off the top of my head except the corner case of aboriginal title in canada.
While there are easements, rights of way and such with realty, property ownership in general is a much more absolute right than ownership of most IPR:
In actual fact, in most common law jurisdictions real property is not owned absolutely - the state always owns the underlying title - This is known as fee simple ownership. This is what gives the state rights like taxation, escheat etc..
Also if you look at a land grant the state almost always reserves certain rights (mineral rights and oil and gas are the big ones) that they continue to own, not you.
On the other hand most personal property is owned absolutely (allodial I think is the term) - In some civil law countries the same can apply to land.

The best way to think about property is as a bundle of rights and obligations not as an actual object.
What you describe for real property isn't necessarily true in all cases either: Going through your points one by one:
Property doesn't have to be registered - In some jurisdictions transfers of ownership and ownership of real property does have to be registered. This type of system is known as a Torrens System and is used in Australia, New Zealand, Alberta, and British Columbia just off the top of my head.
Property doesn't have a term after which it expires:
Leasehold property, or life estates do have a time after which ownership expires.
Even freehold property is subject to escheat as well.
Some IPR aren't fully transferable, unlike property:
Hmm nothing off the top of my head except the corner case of aboriginal title in canada.
While there are easements, rights of way and such with realty, property ownership in general is a much more absolute right than ownership of most IPR:
In actual fact, in most common law jurisdictions real property is not owned absolutely - the state always owns the underlying title - This is known as fee simple ownership. This is what gives the state rights like taxation, escheat etc..
Also if you look at a land grant the state almost always reserves certain rights (mineral rights and oil and gas are the big ones) that they continue to own, not you.
On the other hand most personal property is owned absolutely (allodial I think is the term) - In some civil law countries the same can apply to land.