From The Collaborative International Dictionary of English v.0.48 :
bachelor-at-arms \bachelor-at-arms\ n.
a knight of the lowest order; he was permitted to display
only a pennon.
Syn: knight bachelor, bachelor
[WordNet 1.5]
From WordNet (r) 3.0 (2006) :
bachelor-at-arms
n 1: a knight of the lowest order; could display only a pennon
[syn: knight bachelor, bachelor-at-arms, bachelor]