late 14c., "an introduction to the canon of the Mass," also "statement or statements introducing a discourse, book, or other composition; series of preliminary remarks, written or spoken," from Old French preface "opening part of sung devotions" (14c.) and directly from Medieval Latin prefatia, from Latin praefationem (nominative praefatio) "fore-speaking, introduction," in Medieval Latin "prologue," noun of action from past participle stem of praefari "to say beforehand," from prae "before" (see pre-) + fari "speak," from PIE root *bha- (2) "to speak, tell, say."
