A decade is a period of 10 years. The word is derived (via French and Latin) from the Ancient Greek: δεκάς, romanizeddekas, which means a group of ten. Decades may describe any ten-year period, such as those of a person's life, or refer to specific groupings of calendar years.


Any period of ten years is a "decade".[1] For example, the statement that "during his last decade, Mozart explored chromatic harmony to a degree rare at the time" merely refers to the last ten years of Wolfgang Amadeus Mozart's life without regard to which calendar years are encompassed. Also, 'the first decade' of a person's life begins on the day of their birth and ends at the end of their 10th year of life when they have their 10th birthday; the second decade of life starts with their 11th year of life (during which one is typically still referred to as being "10") and ends at the end of their 20th year of life, on their 20th birthday; similarly, the third decade of life, when one is in one's twenties or 20s, starts with the 21st year of life, and so on, with subsequent decades of life similarly described by referencing the tens digit of one's age.

0-to-9 decade

The most widely used method for denominating decades is to group years based on their shared tens digit, from a year ending in a 0 to a year ending in a 9 – for example, the period from 1960 to 1969 is the 1960s,[2] and the period from 1990 to 1999 is the 1990s. Sometimes, only the tens part is mentioned ('60s or sixties, and '90s or nineties), although this may leave it ambiguous as to which century is meant. However, this method of grouping decades cannot be applied to the decade immediately preceding AD 10, because there was no year 0.

Particularly in the 20th century, 0-to-9 decades came to be referred to with associated nicknames, such as the "Swinging Sixties" (1960s), the "Warring Forties" (1940s) and the "Roaring Twenties" (1920s). This practice is occasionally also applied to decades of earlier centuries; for example, referencing the 1890s as the "Gay Nineties" or "Naughty Nineties".

1-to-0 decade

A rarer approach groups years from the beginning of the AD calendar era to produce successive decades from a year ending in a 1 to a year ending in a 0, with the years 1–10 described as "the 1st decade", years 11–20 "the 2nd decade", and so on; later decades are more usually described as 'the st, nd, rd, or th decade of the st, nd, rd, or th century' (using the strict interpretation of 'century').[a] For example, "the second decad of the 12th. Cent." (sic);[3] "The last decade of that century";[4] "1st decade of the 16th century";[5] "third decade of the 16th century";[6] "the first decade of the 18th century".[7] This decade grouping may also be identified explicitly; for example, "1961–1970";[8] "2001–2010";[9] "2021–2030".[10] The BC calendar era ended with the year 1 BC and the AD calendar era began the following year, AD 1. There was no year 0.

Usage methods compared
0-to-9 decade0s10s...2000s2010s2020s...
1-to-0 decade1st decade of the 1st century2nd decade of the 1st century...1st decade of the 21st century2nd decade of the 21st century3rd decade of the 21st century

Public usage of the two methods

A YouGov poll was conducted on December 2, 2019, asking 13,582 adults in the United States, "When do you think the next decade will begin and end?" Results showed that 64% answered that "the next decade" would begin on January 1, 2020, and end on December 31, 2029 (0-to-9 method); 17% answered that "the next decade" would begin on January 1, 2021, and end on December 31, 2030 (1-to-0 method); 19% replied that they did not know.[11]

See also


  1. ^ "Decade". Lexico. 2020. Retrieved 2020-02-26.
  2. ^ "1960s". DEFINITIONS. Retrieved 3 January 2022.
  3. ^ 1837 HALLAM Hist. Lit. I. i. 19. The Compact Edition of the Oxford English Dictionary.
  4. ^ 1878 DOWDEN Stud. Lit. I. The Compact Edition of the Oxford English Dictionary.
  5. ^ "Catalogue of Illuminated Manuscripts". British Library. Retrieved 24 February 2020.
  6. ^ "Illuminated Manuscripts from the Collection of Maurice Burrus (1882–1959)". CHRISTIE'S. Retrieved 24 February 2020.
  7. ^ "French harpsichord music in the first decade of the 18th century". Oxford Academic. Retrieved 24 February 2020.
  8. ^ "Past Poets Laureate: 1961–1970". The Library of Congress. Retrieved 24 February 2020.
  9. ^ "Milestones 2001–2010". United Nations. Retrieved 24 February 2020.
  10. ^ "Solar Eclipses: 2021–2030". NASA. Retrieved 24 February 2020.
  11. ^ "In recent years, there has been debate around when a decade begins and ends. When do you think the next decade will begin and end?". YouGov. Retrieved 21 December 2019.


  1. ^ There are two ways of thinking about when a century begins and ends. The "strict" viewpoint counts centuries from −01 to −00, while the "popular" viewpoint counts centuries from −00 to −99. For example, the "first decade of the 19th century" may mean either 1801–1810 (if used in "strict" terms) or 1800–1809 (if used in "popular" terms). See century for more information.

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