a public holiday in some parts of the Commonwealth (but not Britain), celebrated every year on Queen Elizabeth II’s Official Birthday . Until 1966 it was celebrated on Queen Victoria’s birthday (24 May). Before 1958 it was called Empire Day.
COMMONWEALTH DAY
Meaning of COMMONWEALTH DAY in English
Oxford guide to British and American culture English vocabulary. Руководство по британской и американской культуре, Оксфордский английский словарь. 2005