noun pl. anniversaries -·ries

1. the date on which some event occurred in an earlier year
2. the commemoration of such an event on that date in following years

Etymology: ME anniversarie < ML anniversaria (dies), anniversary (day) < L anniversarius < annus, year + versum, pp. of vertere, to turn: see verse

adjective

1. that is an anniversary
2. of or connected with an anniversary