I would like to.ask
@Copernicus to say something here. I think it might help.
Or just make things worse.
You are asking what the word "person" means, but you should first ask what a word meaning is. Otherwise, you are going to get a lot of different answers that pull in very different directions. You can ask what any word means and get the same kind of meandering debate that explores the different things that a word could
"mean". There is nothing special about this particular word that makes it any more or less complicated than, say, discussing what the word "god" means.
What a word means depends on how people use that word to express a bundle of related thoughts. Hence, it can take on a range of meanings that differ according to context. The word "person" means different things in different contexts. That is true of pretty much all words. If you think of a word meaning as a bundle of related concepts or memories, then there is a kind of core sense that is common to a wide range of usage. In different contexts, the peripheral, less commonly associated concepts, become stronger or weaker. For example, in the discussion of what "person" means in the context of abortion, there is a legal sense that is defined by the law. Jimmy Higgins focused on this sense earlier, but WAB said he wasn't interested in a legal definition. Certainly, the parents of a fetus have a very different concept of the growing organism in a mother's womb. That is a person, even if it doesn't have any legal right to own property or be represented by a lawyer. But the key point here is that the meaning of "person" changes, depending on how one uses it to, say, define the usage of other related words in a conversation. So the word "murder" can also mean different things with respect to the status of an individual dying. Is a fetus a "person" in that sense? Then the word "murder" becomes relevant to how we define the usage of a word like "person".
WAB introduced the very interesting question of what it could mean to "unperson" someone. I would say that that word depends very much on what aspect of the meaning of "person" you are focused on. Is it the legal status of the individual or the personal relationship aspect that holds between that individual and those in the relationship? If you don't narrow down the sense of "person" that you are talking about, then you will end up arguing in circles. An "unperson" can merely be someone that people shun. It can also be someone who is brain dead. It depends on what aspect of "person" you want to negate or cancel out.
One last comment, because it always needs to be said. Definitions are very different from meanings. Definitions are about usage, and context defines usage. Definitions are concise descriptions of usage in a context, and there can be as many different definitions of a word as there are types of contexts. Lexicographers go nuts over how many word senses should be in a dictionary entry and how broad or narrow the sense definitions need to be. Meanings are more like encyclopedic, not dictionary, entries. Meanings exist somewhat independently of context, because the semantic load on a word token can shift in many different directions, depending on context of usage. There is a kind of core bundle of concepts with less commonly associated concepts spinning off into different spokes--like the arms of an octopus or the projections of an amoeba. Dictionary definitions will focus on different arms of the semantic octopus.