Meaning of gentleman-at-arms

gen•tle•man-at-arms

Pronunciation: ( jen'tl-mun-ut-ärmz'), [key]
— pl. gen•tle•men-at-arms.
  1. (in England) one of a guard of 40 gentlemen who attend the sovereign on state occasions.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.