anniversary
US /ˌæn.əˈvɝː.sɚ.i/
UK /ˌæn.əˈvɝː.sɚ.i/
1.
the date on which an event took place in a previous year, especially one of historical or institutional importance
:
•
Today marks the 50th anniversary of the company's founding.
•
They celebrated their wedding anniversary with a romantic dinner.