the office of the US President in the White House (1). It has this name because of its shape. The phrase is sometimes also used to mean the President himself:
Congress is waiting to see how the Oval Office will react.
OVAL OFFICE
Meaning of OVAL OFFICE in English
Oxford guide to British and American culture English vocabulary. Руководство по британской и американской культуре, Оксфордский английский словарь. 2005