A prequel is a work that portrays events which inclue the structure, conventions, and/or characters of a previously completed narrative, but occur at an earlier time. The word is a neologism, formed as a portmanteau from pre-, meaning before, and sequel, a work which takes place after a previous one (although the word sequel comes from the Latin verb sequor, there is no verb "prequor"). Its meaning is easily grasped and it has passed into common usage. A similar term would be protosequel, as adopted in other languages, like the Spanish "protosecuela".