anniversary - * Birthdays (v.) are the most common type of anniversary, where the birth date of a person is commemorated annually. The actual celebration is sometimes moved for practical reasons, as in the case of an official birthday. * Wedding anniversaries are also often celebrated on the same day of the year as the wedding occurred. The Latin word dies natalis (literally birth day) has become a common term, adopted in all languages, especially in intellectual and institutional circles, for the anniversary of the founding ('legal or statutory birth') of an institution, such as an alma mater (college or other school). Even in ancient Rome, we know of the [dies] Aquilae natalis ('birthday of the eagle', anniversary of the official founding of a legion).