The first usages of the word chivalry in the English language were around the turn of the fourteenth century, when there was still a lot of variation. This led to attestations like chivalrie, cheualry, cheuelry, cheualrie, chewalrye, chiualrie, and more, and there were almost as many definitions as spellings. At the beginning, it didn't necessarily refer to the honor code of knights: it could mean "knighthood" or "warfare", it could refer to a tenure of land, and, earliest on, it meant "cavalry". Through Old French chevaler (also the source of our word cavalry), the term traces to Latin caballarius, which meant "horseman". The root there is caballus ("horse"), which has a disputed etymology. One theory is that it could have been borrowed from a Gaulish word, meaning it would go back to Proto-Celtic, but it also might be Slavic or Greek - there are confusing cognates all throughout the Indo-European languages.
Hello! I'm Adam Aleksic, a sophomore studying government and linguistics at Harvard University, where I co-founded the Harvard Undergraduate Linguistics Society. In addition to etymology, I also really enjoy politics, vexillology, geography, board games, conlanging, and law.