Source : Webster's Revised Unabridged Dictionary (1913)

Black Rod \Black" Rod`\
   (a) the usher to the Chapter of the Garter, so called from
       the black rod which he carries. He is of the king's
       chamber, and also usher to the House of Lords. [Eng.]
   (b) An usher in the legislature of British colonies.
       --Cowell.

             Committed to the custody of the Black Rod.
                                                  --Macaulay.