You make some very good points, mate. I agree that defining slavery only as compulsory work is not enough and they must be also defined as property for the reasons you mentioned. But I would also have to enforce such rigor into your own vocabulary because the same reason that conscripts are slaves in almost everything except not being property, and yet still clearly are not slaves, thus we must also define outlaws as clearly not slaves. Neither carry the perfect prerrequisites of slavery, which we both defined as
1) forced labour being imposed on you
2) being considered property.
Both rigorously need to be true for a person to be a slave or else we enter into the problem of conscripts and outlaws.
That being said, with this definition we both agreed on, we cannot define a person with no rights as a slave because having no rights does not mean you necessarily are being forced to do labor or are seen as property. All it means is you do not have any guarentee that you will not be treated as such (that is what I meant by accepting it, in the sense that you are forced to it. There is a period before being forced to something in which you can choose to flee or resist and in which period you are not typically considered a slave). It might sound corny and Kanya West'y but it is pretty much a valid point in the sense that you really can't consider someone a slave if you haven't caught him yet or do you disagree?
With that said I still recommend calling the Slave-by-default the Outlaw-by-default, in order to maintain consistency on what we have agreed upon.
In the context of the actual members of an entity, it is very much Slavery-By-Default. I would define slavery as what happens when you integrate an individual into your society by placing them under your control and requiring them to do work but without giving them the legal rights and status of a rank-and-file member of your society.
An outlaw does not have rights, but an an outlaw is also *not* part of your entity so he is not a slave. Basically I am defining slavery as when you make outlaws part of your society but without making said outlaws not outlaws in the process. So random people who do not have any status in your society are made part of your society but not the reverse, your society is not made part of them.
Under Slavery-By-Default slaves are outlaws but outlaws are not slaves.