The Collaborative International Dictionary of English v.0.48:

Gendarme \Gen`darme"\, n.; pl. Gendarmes, or Gens d'armes.
   [F.]
   1. (Mil.) One of a body of heavy cavalry. [Obs.] [France]
      [1913 Webster]

   2. An armed policeman in France. --Thackeray.
      [1913 Webster]