Today we’re looking at -rect words that are related to ruling, because the “moving in a straight line” part of the Proto Indo European origin word is taken very seriously.
Rule showed up in the thirteenth century from the Old French riule (noun) and riuler (verb). They come from the Vulgar and classical Latin regula, rule, from regere, to rule. Royal showed up in the mid thirteenth century from the Old French roial and classical Latin regalis, which just meant royal, so not a huge stretch here. I guess French is the language responsible for getting rid of all the Gs.
Reign and regent have similar origins, with the former showing up in the early thirteenth century as a noun and later on as a verb. The noun is from the classical Latin regnum, kingdom, and the verb from regnare, to rule. Regent showed up later, in the fifteenth century, from the Medieval Latin regentem and classical Latin regens, which just means regent. At least we still pronounce the G in this one.
Finally today we’re looking at rank. But not the rank that has to do with a division or class, because that comes from a completely different place. No, I mean the rank like something you smell. It comes from the Old English ranc, which meant bold, courageous,showy, or mature. That’s from the Proto Germanic rankaz, which is thought to be from reg-, although that’s not sure. It’s thought that it went from showy to excessive to unpleasant to loathsome, but I have no idea how the straight/direct line thing is worked in there. It would actually make more sense if the other version of rank was related, but of course it’s not.
Tony Jebson’s page on the Origins of Old English