A retronym is a newer name for an existing thing that distinguishes the original/older form from a more recent/newer one. Retronyms are everywhere: ‘physical book’, ‘independent bookstore’, ‘hard copy’, ‘mainstream media’. All books used to be physical, all bookstores independent (whatever that means), all copies hard, and there was only one kind of media.
Retronyms are more than words. They represent a perspective on things and a view on culture. A view from somewhere. And they track cultural and technological change.
Retronym-ing (or retronaming?) a word is usually done using an adjective, as in the examples above. ‘Retronym-ing’ occurs because of diversification and cultural change. Not all diversification is cultural change. There is no need for books to be called physical if electronic or audio books weren’t so popular. The pressure to come up with a retronym is a concession made by the newer to the older.
Retronyming happens because of retrofitting, which is its cause as well as its opposite. Retrofitting is when an older system acquires newer technology, or an older item acquires a new form. Books keep all of their main features but also become digital. Older tech reacts and pushes for qualifiers such as ‘physical’, ‘classic’, ‘traditional’. A new type of media emerges, breaking away from the mainstream. That’s when we notice there was a main stream in the first place.