An anniversary is the date on which an event took place or an institution was founded in a previous year, and may also refer to the commemoration or celebration of that event. For example, the first event is the initial occurrence or, if planned, the inaugural of the event. One year later would be the first anniversary of that event. The word was first used for Catholic
feasts to commemorate saint
Most countries celebrate national anniversaries, typically called national day
s. These could be the date of independence of the nation or the adoption of a new constitution
or form of government. The important dates in a sitting monarch's reign may also be commemorated, an event often referred to as a "jubilee
s are the most common type of anniversary, on which someone's birthdate is commemorated each year. 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.
* Death anniversaries
phrase ''dies natalis
'' (literally "birth day") has become a common term, adopted in many 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). In ancient Rome, the ''ies
Aquilae natalis'' was the "birthday of the eagle", the anniversary of the official founding of a legion.
Anniversaries of nations are usually marked by the number of years elapsed, expressed with Latin words or Roman numerals.
Latin-derived numerical names
Latin terms for anniversaries are mostly straightforward, particularly those relating to the first twenty years (1–20), or multiples of ten years (30, 40, 50, 60, 70 etc.), or multiples of centuries or millennia (100, 200, 300, 1000, 2000, 3000, etc.) In these instances, the name of the anniversary is generally derived from the Latin word(s) for the respective number of years. However, when anniversaries relate to fractions of centuries (125, 150, 175, 250 years—i.e. 1.25, 1.5, 1.75, and 2.5 centuries), the situation is not as simple.
were based on a duodecimal system
. From to they were expressed as multiples of twelfths (''uncia
'' "twelfth"; the source of the English words ''inch'' and ''ounce'') and from to they were expressed as multiple twelfths less than the next whole unit—i.e. a whole unit less , or respectively. There were also special terms for quarter (''quadrans
''), half (''semis
''), and three-quarters (''dodrans
'' is a Latin contraction of ''de-quadrans'' which means "a whole unit less a quarter" (''de'' means "from"; ''quadrans'' means "quarter"). Thus for the example of 175 years, the term is a quarter century less than the next whole (bi)century or 175 = (−25 + 200).
In Latin, it seems that this rule did not apply precisely for 1½. While ''secundus'' is Latin for "second", and ''bis'' for "twice", these terms are not used such as in sesqui-secundus. Instead ''sesqui'' (or ''ses'') is used by itself.
Many anniversaries have special names. ''Etiquette in Society, in Business, in Politics and at Home'' by Emily Post
, published in 1922, contained suggestions for wedding anniversary gifts for 1, 5, 10, 15, 20, 25, 50, and 75 years.
Wedding anniversary gift suggestions for other years were added in later editions and publications; they now comprise what is referred to as the "traditional" list. Generally speaking, the longer the period, the more precious or durable the material associated with it. See wedding anniversary
for a general list of the wedding anniversary symbols; however, there are variations according to some national traditions.
Furthermore, there exist numerous partially overlapping, partially contradictory lists of anniversary gifts (such as wedding stones), separate from the 'traditional' names.
The concepts of a person's birthday stone
and zodiac stone, by contrast, are fixed for life according to the day of the week, month, or astrological sign corresponding to the recipient's birthday
* List of historical anniversaries
* Quinquennial Neronia
* Wedding anniversary