: a person who determines the forms to be observed on a public occasion or superintends their observance: as
a. : a court official of high rank in charge of the reception of ambassadors and other matters of protocol
b. : an official at solemn services of the Roman Catholic Church charged with the duty of seeing that all the rites are correctly executed
c. : a person who acts as host at a formal event (as a banquet or graduation exercise) making the welcoming speech, introducing speakers, and being generally responsible for the conduct of the program
d. : a person who acts as a host for a variety program or other stage entertainment introducing other performers to the audience and usually interspersing his introductions with jokes, songs, or other specialty acts