Source : Webster's Revised Unabridged Dictionary (1913)

Anniversary \An`ni*ver"sa*ry\, a. [L. anniversarius; annus year
   + vertere, versum, to turn: cf. F. anniversaire.]
   Returning with the year, at a stated time; annual; yearly;
   as, an anniversary feast.

   {Anniversary day} (R. C. Ch.). See {Anniversary}, n., 2.

   {Anniversary week}, that week in the year in which the annual
      meetings of religious and benevolent societies are held in
      Boston and New York. [Eastern U. S.]

Anniversary \An`ni*ver"sa*ry\, n.; pl. {Anniversaries}. [Cf. F.
   anniversaire.]
   1. The annual return of the day on which any notable event
      took place, or is wont to be celebrated; as, the
      anniversary of the Declaration of Independence.

   2. (R. C. Ch.) The day on which Mass is said yearly for the
      soul of a deceased person; the commemoration of some
      sacred event, as the dedication of a church or the
      consecration of a pope.

   3. The celebration which takes place on an anniversary day.
      --Dryden.

Source : WordNet®

anniversary
     n : the date on which an event occurred in some previous year
         (or the celebration of it) [syn: {day of remembrance}]