So what is the recommended alternative terminology? For example, how would you characterize the type of collaboration that happens in Google Docs, or the type of communication that happens in a chat?

I'm not a web developer, so I wouldn't be the best person to ask, but the key aspect is that the server pushes data to the browser as soon as it gets it rather than waiting for it to be requested, right? You could call it "low-latency push" or "low-latency remote interaction" or something like that.

Or you could cut to the chase and call it "websockets." socket.io supports other technologies for ancient browsers, but that's a detail that could be addressed in the post.

I think it would be fine to contextualize it as "collaboration". E.g., "real-time collaboration app". You might also say immediate, instant, simultaneous, or live collaboration. Or you could be more specific about the context. Etherpad, for example describes itself as "Etherpad allows you to edit documents collaboratively in real-time, much like a live multi-player editor that runs in your browser."