返璞词是在人类语言的发展过程中某些词语经过演变词义产生扩大或变化，为了加以区别产生的新词。通常是对原有的名词加上定语来修饰。

如：

A retronym is a new name for something that differentiates the original from a more recent form or version.

Advances in technology are often responsible for retronym coinage. For example, the term "acoustic guitar" was coined at the advent of electric guitars and analog watches were thus named to distinguish them from digital watches.