It’s love day, so I might as well look at words of love. Otherwise I’ll have to wait until the next time that February 14th ends up on an etymology day.
Love comes from the Old English lufu, which was pronounced something like “luhvuh”, and is clearly way more fun to say. It comes from Proto Germanic lubo, which is from the Proto Indo European leubh-, which means to care, desire, or love and is the origin word for things like libido (makes sense) and believe (What??). The Old English verb form of the word was actually lufian, which is actually pronounced like “loovian”. Why did we change this???
Passion showed up in the late twelfth century but back then it was only in a Christian context, and it took a few decades for it to mean “strong emotion”, and then things like sexual love and strong liking. It comes from the Old French passion and Late Latin passionem, suffering or enduring, and can be traced to the classical Latin pati, to suffer. I really want to know what happened in those few centuries that made it turn from suffering to strong emotion, because that sounds like a hell of a leap.
Adore showed up in the late fourteenth century as aouren, no d, coming from the Old French aorer, to adore. It does have a d in its classical Latin form, adorare, which could mean to adore but also speak to formally or ask in prayer. See, the ad- means to here, and orare means to speak or to pray. Adoring something is praying to it. Kind of.
Ardor showed up in the mid fifteenth century from the Old French ardure, heat, glow, or passion. Before that it was the classical Latin ardorem, heat. Like, literally heat, but also sometimes figuratively, which is how we got the current definition of ardor. It can also be traced back to the Proto Indo European as-, burn or glow, another word that shows up in quite a few places. Which we will be getting to another time.
Tony Jebson’s page on the Origins of Old English