Evolution happens. Things can evolve over millions of years, or like language, words can change in just a few years, sometimes just a few months or weeks if the usage catches on quickly. While new words spring up all the time for completely brand new discoveries, concepts or things, what happens to the old words for objects that have evolved into similar, but new concepts? They become retronyms.
A retronym is a new word or phrase for an old word that was created to distinguish the old word from its recent form, use or version.
For example, analog watch is a retronym for the word watch. With the advent of digital watches, the word watch could now mean two objects. Therefore, the retronym phrase analog watch sprang up to refer to the old object which was no longer unique.
This change of language happens without most of us even noticing, mainly because most of us are constantly evolving along with language. Although it is happening right in front of our faces, unless we actually pay attention to it, we are blind to it. But it is fun to think of common words that we use now that have changed just in our lifetimes.
Other examples of retronyms would be: landline phone (needed because of the advent of cell phones); acoustic guitar (needed to distinguish from a electric guitar); World War I (needed when the world went to war a second time). We do not think about these changes because we evolve along with them.
Can you think of other retronyms?