70 years ago today, less than a year after assuming the throne, Britain’s Edward the Eighth performed his last official act as monarch: he gave his royal assent to His Majesty’s Declaration of Abdication Act, 1936. This act, which had followed the King’s address the night before, in which he told the nation he "found it impossible to carry the heavy burden of responsibility and to discharge my duties as king as I would wish to do without the help and support of the woman I love," marked the first (and to date, only) voluntary renunciation of the British monarchy. (来源：英语学习门户网站EnglishCN.com)

Why do we call that act an abdication rather than a renunciation? Renunciation and abdication (not to mention resignation) are all used to describe the act of "giving up a position with no possibility of resuming it." Resignation applies to the "giving up of an unexpired office or trust;" one might resign from the local planning board, for example. Abdication implies a "giving up of sovereign power or sometimes an evading of responsibility" (as when a frustrated parent abdicates responsibility for his wayward child). Then there’s renunciation, whose connotations are similar to that of abdication but which often has an additional implication, that of a sacrifice for a greater end (as when a politician renounces her affiliation with a segregated club).