word-forming element meaning "before," from Old French pre- and Medieval Latin pre-, both from Latin prae (adverb and preposition) "before in time or place," from PIE *peri- (source also of Oscan prai, Umbrian pre, Sanskrit pare "thereupon," Greek parai "at," Gaulish are- "at, before," Lithuanian prie "at," Old Church Slavonic pri "at," Gothic faura, Old English fore "before"), extended form of root *per- (1) "forward," hence "beyond, in front of, before."
The Latin word was active in forming verbs. Also see prae-. Sometimes in Middle English muddled with words in pro- or per-.
mid-15c., "consequence of an event or action, a corollary; that which follows and forms a continuation," from Old French sequelle, sequele (14c.) and directly from Late Latin sequela "that which follows, result, consequence," from sequi "to follow, come after, follow after, attend, follow naturally" (from PIE root *sekw- (1) "to follow").
Specifically "a story that follows and continues another" by 1510s.
Also in Middle English "offspring, issue descendants;" also "train of followers, retinue." Beerbohm uses sequelula "a small sequel" (1912).
<a href="https://www.etymonline.com/word/prequel">Etymology of prequel by etymonline</a>
Harper, D. (n.d.). Etymology of prequel. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/prequel