equerry
An officer responsible for the care and supervision of the horses of a person of rank.
A personal attendant to a head of state, a member of a royal family, or a national representative.
A bedroom is provided for the equerry and one for the King's physician. […] The compartments for the doctor and equerry are panelled in West African betula and cherry mahogany.
Where it comes from
From an alteration of earlier esquiry (through the influence of the unrelated Latin equus), from Middle French escuirie, escuerie, derivative of escuyer (“squire”), or alternatively from Medieval Latin scuria (“stable”), from Old High German scura (“barn”). Compare esquire.
Adapted from the Wiktionary entry equerry (CC BY-SA 4.0).