'man-at-arms' definitions:

Definition of 'man-at-arms'

(from WordNet)
noun
A heavily armed and mounted soldier in medieval times

Definition of 'man-at-arms'

From: GCIDE
  • man-at-arms \man-at-arms\ n.; pl. men-at-arms. A heavily armed and sometimes mounted soldier in medieval times. [WordNet 1.5]