officiate /əˈfɪ.ʃi.eɪt/verb 2noun 1forms 3 verb2 •To perform the functions of some office.She officiated as registrar at the wedding.She officiated the wedding as registrar. •To serve as umpire or referee.This is the second time he has officiated at a cup-final.He's never officiated a cup-final before. noun1 •(rare) A person appointed to office, an official. formsofficiated · officiating · officiates