An Etymological Dictionary of Astronomy and Astrophysics

1. General: To make, put, or set right; to correct.
   
2. Electricity: To convert an → alternating current into a → direct current.
   
3. Chem.: To refine a substance, especially by repeated distillation or sublimation.

Etymology (EN): M.E. rectifien, from O.Fr. rectifier “to make straight,” from L.L. rectificare “make right,” from L. rectus “straight,” cognate with Pers. râst, as below, → right + root of
facere “to make, do, perform” (cf. Fr. faire, Sp. hacer), from PIE base *dhe- “to put, to do” (cf. Mod.Pers. dâdan “to give;” O.Pers./Av. dā- “to give, grant, yield,” dadāiti “he gives; puts;” Skt. dadáti “puts, places;” Hitt. dai- “to place;” Gk. tithenai “to put, set, place;” Lith. deti “to put;” Czech diti, Pol. dziac’, Rus. det’ “to hide,” delat’ “to do;” O.H.G. tuon, Ger. tun, O.E. don “to do”).

Etymology (PE): Râstidan, literally “to make straight, right,” infinitive from râst cognate with L. rectus “straight,” → right.