anniversary
Pronunciation:
/ˌænɪˈvɜːs(ə)ɹi//ˌænəˈvɝs(ə)ɹi/noun
Definitions
A day that is an exact number of years (to the day) since a given significant event occurred. Often preceded by an ordinal number indicating the number of years.
Example: Today is the fiftieth anniversary of the end of the war.
(loosely) A day subsequent in time to a given event by some significant period other than a year (especially as prefixed by the amount of time in question).