A "CoLocation" or "CoLoc" for short. Coin a short, memorable term, then use both terms everywhere until your users have been around for a time. As a user gets

A "CoLocation" or "CoLoc" for short. Coin a short, memorable term, then use both terms everywhere until your users have been around for a time. As a user gets more experienced on the site, drop the longer term and use the "jargon" term. It's a novel concept, it deserves a neologism.