What is the origin of apparatus?

Apparatus “a complex instrument for a particular purpose” is a borrowing of Latin apparātus “equipment, act of equipping, preparation.” Using the suffix -tus, which indicates verbal action, apparātus—literally meaning “equipped (thing)”—is the past participle of the verb apparāre “to equip, make ready,” from parāre “to prepare.” The stems of parāre, para- and pera-, appear in a wide variety of Latin-derived terms, from imperative and preparation to vituperate and separatist. As a result of the regular sound changes that emerged as Latin evolved into French, parāre still exists today, albeit in disguise, in French-derived terms such as empire, rampart, repair, spar, and even sever. Apparatus was first recorded in English in the 1620s.