Main Entry: an·ni·ver·sa·ry

Pronunciation: \ˌa-nə-ˈvərs-rē, -ˈvər-sə-\

Function: noun

Inflected Form(s): plural an·ni·ver·sa·ries

Etymology: Middle English anniversarie, from Medieval Latin anniversarium, from Latin, neuter of anniversarius returning annually, from annus year + versus, past participle of vertere to turn — more at annual, worth

Date: 13th century

1 : the annual recurrence of a date marking a notable event; broadly : a date that follows such an event by a specified period of time measured in units other than years <the 6-month anniversary of the accident>
2 : the celebration of an anniversary