Inauguration Day
noun
the day on which the president of the United States is inaugurated, being January 20 of every year following a year whose number is divisible by four. Prior to the Twentieth Amendment to the Constitution (ratified February 6, 1933), it was March 4.
British Dictionary definitions for inauguration day
Inauguration Day
noun
the day on which the inauguration of a president of the US takes place, Jan 20