syllabus (n.)

1650s, "table of contents of a series of lectures, etc.," from Late Latin syllabus "list," ultimately a misreading of Greek sittybos "parchment label, table of contents," of unknown origin. The misprint appeared in a 15c. edition of Cicero's "Ad Atticum" (see OED). Had it been a real word, the proper plural would be syllabi.