1) Ancient Roman government 
officer in court who attends to execute orders; harbinger
• (n.) Formerly, an officer who attended magistrates and judges to execute their orders. • (n.) A messenger or officer who serves the process of an ecclesiastical court.
In Roman times, an attendant on magistrates who saw to the execution of their orders; in the modern English ecclesiastical courts, the officer who serves processes of the court and causes defendants...
Ap·par'i·tor noun [ Latin , from apparere . See Appear .] 1. Formerly, an officer who attended magistrates and judges to execute their orders. « Before any of his apparitors could execute the sentence, he was himself summoned away by a sterner apparitor to t...
archaic or obsolete terms > Occupations:Official who summoned witnesses in the ecclesiastical courts.
(in ancient Rome) a subordinate official of a magistrate or of the court.