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]