FWIW, I don’t think the meaning has been lost; I think the squeaky wheel people on social media have forgotten the meaning when they fail about “the US isn’t a democracy because we have a Senate/electoral process/etc” but I think that’s a pretty narrow slice of people and I think it’s more ignorance than a changed meaning. In my experience, most people seem to agree that representative democracies are also democracies (indeed, even the ignorant people would usually admit that most European countries are democracies despite having a similar bicameral system to the US).