The English word "chivalry" hides a horse inside it. It comes from the Old French chevalerie, the body of practices and ideals associated with a chevalier — literally a "horseman" or "knight." The root is cheval ("horse"), itself from late Latin caballus, a colloquial word for a working horse that displaced the more formal equus.
Why the Horse Mattered
In medieval Europe, owning, equipping, and training a war horse was so expensive that only the landed elite could do it. The mounted warrior — the knight — was, by definition, rich. The word chevalerie originally meant simply "the class of mounted warriors" — a description, not a moral category. The ethical content — courage, courtesy, generosity, protection of the weak — accumulated over time as troubadours and clerics turned the role of the knight into a literary ideal.
A Family of Horse Words
The Latin caballus sired a sprawling family of words across the Romance and English languages. Modern Spanish caballero ("gentleman, knight"), Italian cavaliere, French chevalier. In English we have cavalry, cavalier (originally a horseman), cavalcade, and the surname Chevalier. Equus contributed a different family: equestrian, equine, equitation. The two roots have coexisted in English for centuries, with the more colloquial caballus branch winning the everyday vocabulary.
From Battle to Courtesy
By the late Middle Ages, "chivalry" had broadened from a description of mounted warriors to a more abstract ideal of conduct — one that included how a knight treated his lord, his enemies, and (in courtly literature) the women in his life. By the 18th and 19th centuries, the word had detached almost entirely from horses and warfare. Today "chivalry" most often refers to old-fashioned courtesy, particularly toward women. The horseman is buried inside the word, but he has not ridden anywhere in a long time.