So you’re in your friend’s Dungeons and Dragons campaign, set in a fantasy version of medieval Europe. You haven’t come across any guns, feudalism is everywhere, there have been Monty Python and the Holy Grail references every ten minutes for the last three hours. Your character is a paladin, a holy knight in shining armor. Sure, there are plenty of anachronisms to be expected in this situation, but one of them you might not expect is the existence of a knight in shining armor at all.
“Knight” as a word started out meaning “servant,” and didn’t even necessarily mean a soldier until 1100 AD, 700 years after the beginning of the dark ages and only a couple hundred years out from the Rennaissance. Even then, it was a loosely-defined word, basically just “cavalryman,” and didn’t carry any connection to nobility until the medieval period was already ending in the 1500s. That is after Columbus discovered America. There are similar timelines for chevalier and caballaro and other translations, too. If you ever imagine a person getting “knighted” and then insisting on being called “sir” like a title, and that person doesn’t know where Florida is, you’re picturing history wrong.
Image Source: By Saffron Blaze [CC BY-SA 3.0], from Wikimedia Commons
Meaning “military follower of a king or other superior” is from c. 1100. It began to be used in a specific military sense in the Hundred Years War, and gradually rose in importance until it became a rank in the nobility from 16c.
Online Etymology Dictionary: Knight
cavalier (n.): 1580s, “a horseman,” especially if armed, from Italian cavalliere “mounted soldier, knight; gentleman serving as a lady’s escort,” […]
Online Etymology Dictionary: Cavalier
chivalrous (adj.): mid-14c., “pertaining to chivalry or knight-errantry,” from Old French chevaleros “knightly, noble, chivalrous,” from chevalier (see chevalier; also compare chivalry). According to OED, obsolete in English and French from mid-16c. Not revived in French, but brought back in English 1770s by romantic writers with a sense of “having high qualities (gallantry, courage, magnanimity) supposed to be characteristic of chivalry.”
Online Etymology Dictionary: Chivalrous
Miscellaneous 