The important dates in a sitting monarch's reign may also be commemorated, an event often referred to as a "Jubilee".The Latin 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).
It is a coined word for an anniversary of 175 years, but the elements of the word literally refer to an anniversary of 35,000 years, as follows: septaquinta- (70) × quinque- (5) × centennial (100 years)To express 2½ in Latin it would be expressed as "half-three".
The term relates to being halfway [from the second] to the third integer.
For 350 years it relates to being halfway from the third to the fourth integer; thus a contraction of semis (halfway) and quartus (fourth); hence Sesquarcentennial. 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.
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.
The basic element of most solar symbols is the circular solar disk.
The disk can be modified in various ways, notably by adding rays (found in the Bronze Age in Egyptian depictions of Aten) or a cross.
Latin terms for anniversaries are mostly straightforward, particularly those relating to the first twenty years (1–20), or multiples of ten years (30, 40, 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. There were also special terms for quarter (quadrans), half (semis), and three-quarters (dodrans).
In Latin this is "Sestertius" which is a contraction of semis (halfway) tertius (third)—hence Sestercentennial.