IPA: /ˌænɪˈvɜːrsəri/
KK: /ænɪˈvɜrsəri/
A special day that is remembered or celebrated each year because something important happened on that date in the past.
We celebrated our wedding anniversary with a nice dinner.
Anniversary is formed from "annus" (meaning year) and "versus" (meaning turned). The word refers to the date on which an event occurs every year, marking the turning of another year since that event.
Think of 'year' ('annus') and 'turned' ('versus') to remember that an anniversary is the yearly turning of a date marking an event.