Definition of: anniversary

(an′ə·vûr′sər·ē) noun plural ·ries
1. A day separated by a year or by an exact number of years from some past event.
2. A commemorative observance or celebration on such occasion. Wedding anniversaries are popularly named from the character of the presents regarded as appropriate to their celebration: paper anniversary (1st), wooden anniversary (5th), tin anniversary (10th), crystal anniversary (15th), china anniversary (20th), silver anniversary (25th), golden anniversary (50th), diamond anniversary (60th and 75th).
—adjective
1. Recurring annually or at the same date every year.
2. Pertaining to or occurring on an anniversary. [ < L anniversarius < annus year + versus, pp. of vertere turn]