prepare: [15] Latin parāre ‘make ready’ lies behind a wide range of English words, from apparatus and apparel to emperor and separate. It combined with the prefix prae- ‘before’ to produce praeparāre ‘make ready in advance’, adopted into English via Old French preparer. => apparatus, apparel, emperor, separate[prepare etymology, prepare origin, 英语词源]
mid-15c., a back formation from preparation and in part from Middle French preparer (14c.), from Latin praeparare "make ready beforehand" (see preparation). Related: Prepared; preparing. Be prepared as the Boy Scouts' motto is attested from 1911.