n (obsolete) A serve | serving boy – a youth attending a person of high degree, especially at courts, as a position of honor and education.
n (British) A youth employed for doing errands, waiting on the door, and similar service in households.
n (US) A boy employed to wait upon the members of a legislative body.
n (context|in libraries) The common name given to an employee whose main purpose is to replace materials that have either been checked out or otherwise moved, back to their shelves.