equerry n.

royal officer, especially one charged with care of horses, 1590s, short for groom of the equirrie, from esquiry "stables" (1550s), from French escuerie (Modern French écurie), perhaps from Medieval Latin scuria "stable," from Old High German scura "barn" (German Scheuer); or else from Old French escuier "groom," from Vulgar Latin *scutarius "shield-bearer." In either case, the spelling was influenced by Latin equus "horse," which is unrelated.