The idea of slavery being the main social construct of the entire world in every population segment up until the beginning of the 1800's doesn't mean it mean slaves real property. From the social and "legal" standpoints of the slave owners it does, but from the perspective of the slaves themselves it doesn't. Ownership is only a thing when everyone agrees to it and you posses it. We are talking academia concepts here. This is because property ownership is solely a social concept but also a natural right as well. You technically can't "own" something that someone else has laid claim to. Slaves that are not willing slaves lay claim to their own body even under duress. That is why will is key component here. Again, this is a tangential point to the OP and what I was talking about originally. As you said it is very ancillary and basically a strawman argument because of it being ancillary. Eski is good at those. For me personally if a person wants to be a "slave" and be property to someone else that accepts them as a "slave" then that matters not to me. Many a person still do this to this day as married couples under various religions like Muslims. Now, I will state in many cases it is against the will of the woman so I am against that, but there are plenty of women that love the concept. If they want it then more power to them. I am not saying real slavery doesn't exist or it isn't evil. It exist even today and certainly is the epitome of evil.
Speaking of side notes, the political compass is as useful as a horoscope from the newspaper. Don't read too much into it as the concepts overlap too much or are literally contrary to real concepts.
Lastly, I did make a mistake earlier in this thread when comparing liberal to conservative. It should have been progressive to conservative. Progressive means to make changes on the status quo no matter what. Conservative is the opposite. Liberal is to favor constructs that lean towards both individual and social freedoms. Classical liberal is more about individual freedoms and new wave liberals are about social freedoms. Sometimes those two align, but many times they don't.
The last thing about the american political system is we have two political parties that are in some ways all encompassing even if stereotypical. Democrats and Republicans. Democrats are more left leaning in political spectrum and Republicans are more right leaning. Democrats more social liberal these days and Republicans more classical liberal. Back in the day the Republican party was the progressives and the party of change. They made that change happen by doing things like abolishing slavery, and bringing about more classical liberal changes. These days, since the societal constructs were "set" by the Republicans in the past, they have become the conservatives as society in America is more right leaning in politics for the last few generations while the Democrat party is more "progressive" for changes as the left leaning party. Again, many shades of gray here and no absolutes. This is a tangent to the original OP asking about the definition of far left and far right, but since most people expect the "complicated" answer I am expanding upon the overall political system in the US in this paragraph for those wanting that answer. I am not pigeon holing anyone these days about who they are based on the political party they identify with. There are classic as well as new wave liberals currently in the Democrat party. As Alexandria Occasional Cortex Smollet (yes I am making fun of her because I think she is a young stupid kid) even stated, the democrat party as is in the US would be two parties really in any other country. Because within the party the opposed ideologies of classic vs new age liberalism don't really overlap much.