Community and the death of meaning

I just read a small discussion on Roundtable; I really like on thing Clay Shirky said.

First, a procedural note: Using my prerogative as Chair, I am banning the word 'community' from this discussion, as it describes too many things too vaguely to be of much use.

Community. Together duty.

It used to be that almost all people lived in small, tightly bound groups. People looked out for each others' welfare, this also meant that people had a duty to abide by local laws and norms. This level of closeness, of deep integration between people, has its downsides, but is a great way to live for those who feel the price is worth it.

In short, it's not a community unless you know everyone's childrens' names. While not literally true, it gets to the point - communities are close and (because of Dunbar's Number) small.

And then, semantic diffusion happened, to the point where people describe all users of the Linux operating system as a community.

Now it's true that language changes. I hardly ever use the word "whom" for example. But how do I talk about concepts that used to have words, but now do not?