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A millennium (plural millennia or millenniums) is a period of 1000 years, [1] sometimes called a kiloyear. It derives from the Latin mille, thousand, and annus, year. It is often, but not always, related to a particular dating system.

1000 or one thousand is the natural number following 999 and preceding 1001. In most English-speaking countries, it is often written with a comma separating the thousands unit: 1,000. In analogy to the term century for '100 years' the time lapse of 1,000 years is sometimes termed, after the Greek root, chiliad. A chiliad of other objects means 1,000 of them.

Year Orbital period of the Earth around the Sun

A year is the orbital period of the Earth moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn, and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked.

Latin Indo-European language of the Italic family

Latin is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets and ultimately from the Phoenician alphabet.


Sometimes, it is used specifically for periods of a thousand years that begin at the starting point (initial reference point) of the calendar in consideration (typically the year "1"), or in later years that are whole number multiples of a thousand years after it. The term can also refer to an interval of time beginning on any date. Frequently in the latter case (and sometimes also in the former) it may have religious or theological implications (see millenarianism).

Millenarianism, from Latin mīllēnārius "containing a thousand", is the belief by a religious, social, or political group or movement in a coming fundamental transformation of society, after which "all things will be changed". Millenarianism exists in various cultures and religions worldwide, with various interpretations of what constitutes a transformation.

Debate over millennium celebrations

There was widespread public debate leading up to the celebrations of the year 2000 as to whether the beginning of that year should be understood (and celebrated) as the beginning of "the" new millennium. Historically, there has been debate around the turn of previous decades, centuries, and millennia. The issue arises from the difference between the convention of using ordinal numbers to count years and millennia (as in "the third millennium"), or cardinally using "the two thousands". The first convention is common in English-speaking countries, but the latter is favoured in, for example, Sweden (tvåtusentalet, which translates literally as the two thousands period). Those holding that the arrival of the new millennium should be celebrated in the transition from 2000 to 2001 (i.e., December 31, 2000 to January 1, 2001) argued that the Gregorian calendar has no year zero, and therefore the millennia should be counted from AD 1. Thus, the first period of one thousand complete years runs from the beginning of AD 1 to the end of AD 1000, and the beginning of the second millennium took place at the beginning of 1001. The "year 2000" has been a popular phrase referring to an often utopian future, or a year when stories in such a future were set, adding to its cultural significance. There was also media and public interest in the Y2K computer bug. The change from 1999 to 2000 was compared to the "rolling over" of zeroes on an odometer. Some people [2] argued that the change of the hundreds digit in the year number, and the zeroes rolling over, created a sense that a new century had begun. This is analogous to the common demarcation of decades by their most significant digits, e.g., naming the period 1980 to 1989 as the 1980s or "the eighties". The ISO 8601 standard is superficially similar to this second viewpoint, but as it includes a "year 0" it is not strictly relevant to the discussion.

Millennium celebrations celebrations of the year 2000

The millennium celebrations were a worldwide, coordinated series of events celebrating the end of 1999 and the start of the year 2000 in the Gregorian calendar. Despite the debate about the correct method of calculating the official changover, these celebrations were generally characterised as marking the end of the 20th century and the 2nd millennium, and the beginning of the 21st century and the 3rd millennium.

Ordinal number order type of a well-ordered set

In set theory, an ordinal number, or ordinal, is one generalization of the concept of a natural number that is used to describe a way to arrange a collection of objects in order, one after another. Any finite collection of objects can be put in order just by the process of counting: labeling the objects with distinct natural numbers. Ordinal numbers are thus the "labels" needed to arrange collections of objects in order.

Utopia community or society possessing highly desirable or perfect qualities

A utopia is an imagined community or society that possesses highly desirable or nearly perfect qualities for its citizens. The opposite of a utopia is a dystopia. One could also say that utopia is a perfect "place" that has been designed so there are no problems.

Stephen Jay Gould argued that the choice between them is arbitrary, and, since the question revolves around rules made by people, rather than a natural phenomenon that is subject to experimental measurement, the matter cannot be resolved. [3] Gould, in his essay Dousing Diminutive Dennis' Debate (or DDDD = 2000) ( Dinosaur in a Haystack ), discussed the "high" versus "pop" culture interpretation of the transition. Gould noted that the high culture, strict construction had been the dominant viewpoint at the 20th century's beginning, but that the pop culture viewpoint dominated at its end. Gould also included comments on adjustments to the calendar, such as those by Dionysius Exiguus (the eponymous "Diminutive Dennis") and the timing of celebrations over different transitional periods.

Stephen Jay Gould American evolutionary biologist and historian of science

Stephen Jay Gould was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read authors of popular science of his generation. Gould spent most of his career teaching at Harvard University and working at the American Museum of Natural History in New York. In 1996, Gould was hired as the Vincent Astor Visiting Research Professor of Biology at New York University, where he divided his time teaching there and at Harvard.

<i>Dinosaur in a Haystack</i> collection of essays by Stephen Jay Gould

Dinosaur in a Haystack (1995) is the seventh volume of collected essays by the Harvard paleontologist Stephen Jay Gould. The essays were culled from his monthly column "The View of Life" published in Natural History magazine, which Gould contributed for 27 years. The book deals with themes familiar to Gould's writing: evolution, science biography, probabilities, and strange oddities found in nature.

Dionysius Exiguus was a 6th-century monk born in Scythia Minor. He was a member of a community of Scythian monks concentrated in Tomis, the major city of Scythia Minor. Dionysius is best known as the inventor of the Anno Domini (AD) era, which is used to number the years of both the Gregorian calendar and the (Christianised) Julian calendar. Some churches adopted his computus (calculation) for the dates of Easter.

The popular [4] approach was to treat the end of 1999 as the end of "a millennium" and to hold millennium celebrations at midnight between December 31, 1999, and January 1, 2000, as per viewpoint 2. The cultural and psychological significance of the events listed above combined to cause celebrations to be observed one year earlier than the formal Gregorian date. [4] However, this does not establish that insistence on the formal Gregorian date is "incorrect". Some event organisers hedged their bets by calling their 1999 celebrations things like "Click" referring to the odometer-like rolling over of the nines to zeroes; another, pragmatic approach was to celebrate "a new millennium" twice.

Odometer instrument that indicates distance traveled by a vehicle

An odometer or odograph is an instrument used for measuring the distance travelled by a vehicle, such as a bicycle or car. The device may be electronic, mechanical, or a combination of the two. The noun derives from the Ancient Greek word ὁδόμετρον, hodómetron, from ὁδός, hodós and μέτρον, métron ("measure"). Early forms of the odometer existed in the ancient Greco-Roman world as well as in ancient China. In countries using Imperial units or US customary units it is sometimes called a mileometer or milometer, the former name especially being prevalent in the United Kingdom and among members of the Commonwealth.

Viewpoint 1: Strict usage

2 BC1 BCAD 12345...9989991000100110021003...199819992000200120022003...299829993000300130023003...
First millennium (1000 years)Second millenniumThird millenniumFourth millennium

Viewpoint 2: General usage

Illustration of years with a 99–00 demarcation (starting AD 1)
1 BCAD 1 2  3  4  5  ... 998999100010011002...19981999200020012002...29982999300030013002
First millennium (only 999 years)Second millenniumThird millenniumFourth millennium

See also

A decade is a period of 10 years. The word is derived from the Ancient Greek: δεκάς, romanized: dekas), which means a group of ten. Other words for spans of years also come from Latin: biennium, triennium, quadrennium, lustrum, century, millennium.

A century is a period of 100 years. Centuries are numbered ordinally in English and many other languages.

Millennialism, or chiliasm, is a belief advanced by some religious denominations that a Golden Age or Paradise will occur on Earth prior to the final judgment and future eternal state of the "World to Come".

Related Research Articles

<i>Anno Domini</i> Western calendar era

The terms anno Domini (AD) and before Christ (BC) are used to label or number years in the Julian and Gregorian calendars. The term anno Domini is Medieval Latin and means "in the year of the Lord", but is often presented using "our Lord" instead of "the Lord", taken from the full original phrase "anno Domini nostri Jesu Christi", which translates to "in the year of our Lord Jesus Christ".

A calendar is a system of organizing days for social, religious, commercial or administrative purposes. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single, specific day within such a system. A calendar is also a physical record of such a system. A calendar can also mean a list of planned events, such as a court calendar or a partly or fully chronological list of documents, such as a calendar of wills.

A calendar date is a reference to a particular day represented within a calendar system. The calendar date allows the specific day to be identified. The number of days between two dates may be calculated. For example, "24 June 2019" is ten days after "14 June 2019" in the Gregorian calendar. The date of a particular event depends on the observed time zone. For example, the air attack on Pearl Harbor that began at 7:48 a.m. Hawaiian time on 7 December 1941 took place at 3:18 a.m. Japan Standard Time, 8 December in Japan.

ISO 8601Data elements and interchange formats – Information interchange – Representation of dates and times is an international standard covering the exchange of date- and time-related data. It was issued by the International Organization for Standardization (ISO) and was first published in 1988. The purpose of this standard is to provide an unambiguous and well-defined method of representing dates and times, so as to avoid misinterpretation of numeric representations of dates and times, particularly when data are transferred between countries with different conventions for writing numeric dates and times.

The Revised Julian calendar, also known as the Milanković calendar, or, less formally, new calendar, is a calendar proposed by the Serbian scientist Milutin Milanković in 1923, which effectively discontinued the 340 years of divergence between the naming of dates sanctioned by those Eastern Orthodox churches adopting it and the Gregorian calendar that has come to predominate worldwide. This calendar was intended to replace the ecclesiastical calendar based on the Julian calendar hitherto in use by all of the Eastern Orthodox Church. The Revised Julian calendar temporarily aligns its dates with the Gregorian calendar proclaimed in 1582 by Pope Gregory XIII for adoption by the Christian world. The calendar has been adopted by the Orthodox churches of Constantinople, Albania, Alexandria, Antioch, Bulgaria, Cyprus, Greece, Poland, and Romania.

Week unit of time

A week is a time unit equal to seven days. It is the standard time period used for cycles of rest days in most parts of the world, mostly alongside—although not strictly part of—the Gregorian calendar.

2nd millennium millennium

The second millennium was a millennium spanning the years AD 1001 to 2000. It encompassed the High and Late Middle Ages of the Old World, followed by the Early Modern period, characterized by the Wars of Religion in Europe, the Age of Enlightenment, the Age of Discovery and the colonial period. Its final two centuries coincide with Modern history, characterized by industrialization, the rise of nation states, the rapid development of science, widespread education, and universal health care and vaccinations in the Western world. The 20th century saw increasing globalization, most notably the two World Wars and the subsequent formation of the United Nations. 20th-century technology includes powered flight, television and semiconductor technology, including integrated circuits. The term "Great Divergence" was coined to refer the unprecedented cultural and political ascent of the Western world in the second half of the millennium, emerging by the 18th century as the most powerful and wealthy world civilization, having eclipsed Qing China and the Islamic World.

Julian day is the continuous count of days since the beginning of the Julian Period and is used primarily by astronomers, and in software for easily calculating elapsed days between two events.

New Years Day Holiday

New Year's Day, also simply called New Year or New Year's, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar.

Ussher chronology

The Ussher chronology is a 17th-century chronology of the history of the world formulated from a literal reading of the Old Testament by James Ussher, the Archbishop of Armagh and Primate of All Ireland. The chronology is sometimes associated with young Earth creationism, which holds that the Universe was created only a few millennia ago by God as described in the first two chapters of the biblical book of Genesis. Ussher fell into disrepute in the 19th century.

A calendar era is the year numbering system used by a calendar. For example, the Gregorian calendar numbers its years in the Western Christian era. The instant, date, or year from which time is marked is called the epoch of the era. There are many different calendar eras such as Saka Era.

A millennium is a period of 1,000 years.

The Holocene calendar, also known as the Holocene Era or Human Era (HE), is a year numbering system that adds exactly 10,000 years to the currently dominant numbering scheme, placing its first year near the beginning of the Holocene geological epoch and the Neolithic Revolution, when humans transitioned from a hunter-gatherer lifestyle to agriculture and fixed settlements. The year 2019 in the Holocene calendar is 12019 HE. The HE scheme was first proposed by Cesare Emiliani in 1993.

Year zero does not exist in the anno Domini system usually used to number years in the Gregorian calendar and in its predecessor, the Julian calendar. In this system, the year 1 BC is followed by AD 1. However, there is a year zero in astronomical year numbering and in ISO 8601:2004 as well as in all Buddhist and Hindu calendars.

The Kurdish calendar was originally a lunisolar calendar related to the Babylonian calendar, but is now a solar calendar related to the Iranian calendar. The current year will begin on 21 March 2019.

The proleptic Gregorian calendar is produced by extending the Gregorian calendar backward to dates preceding its official introduction in 1582. In countries that adopted the Gregorian calendar later, dates occurring in the interim are sometimes "Gregorianized" as well. For example, George Washington was born on February 11, 1731, as Great Britain and its possessions were using the Julian calendar with English years starting on March 25 until September 1752. After the switch, that day became February 22, 1732, which is the date commonly given as Washington's birthday.


  1. "millennium", Oxford Dictionaries (Oxford University Press, 2016).
  2. "When Does the New Millennium Begin?" January 1, 1999.
  3. Gould, Stephen Jay, Questioning the Millennium (New York: Harmony Books, 1997), part 2.
  4. 1 2 Associated Press, "Y2K It Wasn't, but It Was a Party", Los Angeles Times, January 1, 2001.