In linguistics, a libfix is a productive bound morpheme affix created by back-formation, often a generalization of a components of a blended or portmanteau word. For example, walkathon was coined in 1932 as a blend of walk and marathon, and soon thereafter the -athon part was reinterpreted as a libfix morpheme meaning "event or activity lasting a long time or involving a great deal of something". Words formed with this suffix include talkathon, telethon, hackathon, and so on. Affixes whose morpheme boundaries are etymologically based and which are used in their original sense, are not libfixes.