Definition of serjeant-at-arms:
(n) :
(UK) A similar officer who attends on each House of Parliament, and arrests any person ordered by the House to be arrested. The post still exists with respect to the UK House of Commons, but is largely ceremonial.
(n) :
(UK, historical) An officer who attends upon the Lord Chancellor with the mace, and who executes various writs of process in the course of a Chancery suit.
(n) :
Archaic spelling of sergeant-at-arms (“person who keeps order at a meeting”). [A person charged with keeping order at a meeting, especially a meeting of the legislature.]