DVV
Perhaps you should have used the Oxford Dictionary
A
anniversary
Pronunciation:/anɪˈvəːs(ə)ri/
noun (plural anniversaries)
the date on which an event took place or an institution was founded in a previous year:
the 50th anniversary of the Battle of Britain
the 75th anniversary of the RAF
the date on which a couple were married in a previous year:
he even forgot our tenth anniversary!
Origin:
Middle English: from Latin anniversarius 'returning yearly', from annus 'year' + versus 'turning'
Spelling help
Spell anniversary with a double n at the beginning; the ending is -ary.