Undecimber or Undecember is a name for a thirteenth month in a

calendar A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single and specific day within such a system. A calendar is also a phys ...

that normally has twelve months. Duodecimber or Duodecember is similarly a fourteenth month.

Etymology

The word ''undecimber'' is based on the

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

word ''undecim'' meaning "eleven". It is formed in analogy with ''

December December is the twelfth and final month of the year in the Julian and Gregorian calendars and is also the last of seven months to have a length of 31 days. December got its name from the Latin word ''decem'' (meaning ten) because it was or ...

,'' which, though the twelfth month in the

Gregorian calendar The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years diff ...

, derives from ''decem'' meaning "ten". The word ''undecember'' (abbreviated ''Vnde'') is recorded from a Roman inscription according to the

Oxford Latin Dictionary The ''Oxford Latin Dictionary'' (or ''OLD'') is the standard English lexicon of Classical Latin, compiled from sources written before AD 200. Begun in 1933, it was published in fascicles between 1968 and 1982; a lightly revised second edition ...

, which defines it as "a humorous name given to the month following December". Some recent authors report the names "Undecember" and "Duodecember" for the two intercalary months inserted between November and December upon the adoption of the

Julian calendar The Julian calendar, proposed by Roman consul Julius Caesar in 46 BC, was a reform of the Roman calendar. It took effect on , by edict. It was designed with the aid of Greek mathematicians and astronomers such as Sosigenes of Alexandr ...

in 44 BC, including the

World Calendar The World Calendar is a proposed reform of the Gregorian calendar created by Elisabeth Achelis of Brooklyn, New York in 1930. Features The World Calendar is a 12-month, perennial calendar with equal quarters. Each quarter begins on a Sunday ...

Association and

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. This claim has no contemporary evidence;

Cicero Marcus Tullius Cicero ( ; ; 3 January 106 BC – 7 December 43 BC) was a Roman statesman, lawyer, scholar, philosopher, and academic skeptic, who tried to uphold optimate principles during the political crises that led to the esta ...

refers to the months as ''intercalaris prior'' and ''intercalaris posterior'' in his letters. Historian

Cassius Dio Lucius Cassius Dio (), also known as Dio Cassius ( ), was a Roman historian and senator of maternal Greek origin. He published 80 volumes of the history on ancient Rome, beginning with the arrival of Aeneas in Italy. The volumes documented the ...

tells that Licinus,

procurator Procurator (with procuracy or procuratorate referring to the office itself) may refer to: * Procurator, one engaged in procuration, the action of taking care of, hence management, stewardship, agency * ''Procurator'' (Ancient Rome), the title of ...

Gaul Gaul ( la, Gallia) was a region of Western Europe Western Europe is the western region of Europe. The region's countries and territories vary depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the Eas ...

, added two months to the year 15 BC, because taxes were paid by the month. Though not named by Dio, who wrote in

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

August Immanuel Bekker August Immanuel Bekker (21 May 17857 June 1871) was a German philologist and critic. Biography Born in Berlin, Bekker completed his classical education at the University of Halle under Friedrich August Wolf, who considered him as his most promi ...

suggested these might have been called "Undecember" and "Duodecember".

Computing

In the

Java Platform, Standard Edition Java Platform, Standard Edition (Java SE) is a computing platform for development and deployment of portable code for desktop and server environments. Java SE was formerly known as Java 2 Platform, Standard Edition (J2SE). The platform uses Ja ...

, the java.util.Calendar class includes support for calendars which permit thirteen months. Although the

used in most parts of the world includes only twelve months, there exist some

lunar calendar A lunar calendar is a calendar based on the monthly cycles of the Moon's phases ( synodic months, lunations), in contrast to solar calendars, whose annual cycles are based only directly on the solar year. The most commonly used calendar, the Gre ...

s that are divided into synodic months, with an intercalary or "leap" month added in some years. For example, in the

Hebrew calendar The Hebrew calendar ( he, הַלּוּחַ הָעִבְרִי, translit=HaLuah HaIvri), also called the Jewish calendar, is a lunisolar calendar used today for Jewish religious observance, and as an official calendar of the state of Israel. I ...

seven years out of every nineteen (37%) have the "embolismic month" Adar I. The constant java.util.Calendar.UNDECIMBER represents such a month.

Accounting (called "Month 13")

In accounting, a thirteenth month is sometimes used to adjust financial statements for an entire year without affecting monthly results. For example, an organization may wish to adjust its books to reflect the fact that some of its sales and resulting payments due from customers will not be paid. If an organization only does this once per year the organization can attribute these adjustments to "Month 13" so as not to inaccurately post a full year's worth of write offs to one month.

References

External links

{{wiktionarypar, decem, undecim Months Latin words and phrases Java (programming language) libraries

Etymology

Computing

Accounting (called "Month 13")

See also

References

External links