I’m not sure that the correct interpretation is that they had never heard of “authoritarian”. It’s quite possible that people needed clarification to understand if it applied to Trump. Let’s face it, terms like authoritarian and narcissist, and so many more are so blithely bandied about in the media, that they have lost their specific meaning. Is Trump an authoritarian? I don’t think he was in his first term, although he certainly seemed to have those inclinations. Of course, it’s a legitimate concern that he will go full-blown authoritarian in his second term. He’s certainly showing signs already, demanding to bypass the confirmation process for key appointees.