Source : Webster's Revised Unabridged Dictionary (1913)

Equerry \Eq"uer*ry\ (?; 277), n.; pl. {Equerries}. [F. ['e]curie
   stable, for older escurie, escuirie (confused somewhat with
   F. ['e]cuyer, OF. escuyer, squire), LL. scuria, OHG. skiura,
   sc?ra, barn, shed, G. scheuer, from a root meaning to cover,
   protect, and akin to L. scutum shield. See {Esquire}, and cf.
   {Ecurie}, {Querry}.]
   1. A large stable or lodge for horses. --Johnson.

   2. An officer of princes or nobles, charged with the care of
      their horses.

   Note: In England equerries are officers of the royal
         household in the department of the Master of the Horse.