The obvious answer would be that HD stands for High Definition to set it apart from, well, low definition or regular radio signals. After all, isn’t HD radio the audio equivalent of high definition TV – meaning the quality of the signal is so much better?

My source tells me that HD originally stood for hybrid digital. But now, it stands for … nothing. As nearly as I can tell, it’s just a catchy term trademarked by iBiquity, the ubermench of digital radio.

Isn’t that interesting? Two letters that stand for nothing. Could this be a first? We all know that ABC stands for the American Broadcasting Corporation and ESPN stands for Entertainment and Sports Programming Network (or at least is used to stand for that), but HD? Nada. Zip. Zero. No meaning.

Of course, we Americans like things to stand for something so I suppose that people will eventually come to believe that HD does stand for high definition or hybrid digital or highly digital or something.

But the important thing is that HD stands for better sound. Much better sound.