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• decad (archaic)

語源

From 中期英語 decade, from Old French decade, from Late Latin decādem (“(set of) ten”), from Ancient Greek δεκάς (dekás), from δέκα (déka, “ten”). In reference to a span of ten years, originally a clipping of the phrase decade of years. By surface analysis, dec- +‎ -ade. Doublet of decad and dekad.

発音

• (Received Pronunciation) IPA: /ˈdɛkeɪd/, (dated) /dəˈkeɪd/
• (General American, Canada) enPR: dĕk'ād, dəkād', IPA: /ˈdɛkeɪd/, /dəˈkeɪd/
• (General Australian, New Zealand) IPA: /ˈdekæɪd/
• 韻: -eɪd
• Homophone: decayed (one pronunciation)
• (Received Pronunciation, General American, Canada) IPA: /ˈdɛkəd/ (set of ten prayers in a Rosary)

名詞

decade (plural decades)

1. A group, set, or series of ten [from 16th c.], particularly:

   a decade of soldiers

   1. A period of ten years [from 17th c.], particularly such a period beginning with a year ending in 0 and ending with a year ending in 9. [from 19th c.]

      The 1960s was a turbulent decade.

      I haven’t seen my cousin in over a decade!

      • 1992, Rudolf M[athias] Schuster, The Hepaticae and Anthocerotae of North America: East of the Hundredth Meridian, volume V, Chicago, Ill.: Field Museum of Natural History, →ISBN, page viii:

        The repeated exposure, over decades, to most taxa here treated has resulted in repeated modifications of both diagnoses and discussions, as initial ideas of the various taxa underwent—often repeated—conceptual modification.

      • 1979 December, “Museums”, in Texas Monthly, volume 7, number 12, page 22:

        Thru May: 1920s — The Decade That Roared. New exhibition portraying historical events and everyday life during the Roaring Twenties.

      • 2013 March, David S. Senchina, “Athletics and Herbal Supplements”, in American Scientist‎, volume 101, number 2, archived from the original on 16 May 2013, page 134:

        Athletes' use of herbal supplements has skyrocketed in the past two decades.

      • 2020 January 2, Paul Stephen, “A great place to work”, in Rail, page 29:

        Some of these employees have been with the company for decades, which made the company's claims that it offers good training, positive management and excellent job security and benefit packages all the more compelling.

      • 2024, “I Hate It Here”, in The Tortured Poets Department, performed by Taylor Swift:

        We would pick a decade / We wished we could live in instead of this / I'd say the 1830s but without all the racists

      • 2025 July 16, Daniel Dale, “Fact check: Trump tells fictional story about his uncle and the Unabomber”, in CNN‎, archived from the original on 18 July 2025:

        President Donald Trump likes to boast about the brilliance of his late uncle John Trump, who spent decades as a professor of electrical engineering at the renowned Massachusetts Institute of Technology (MIT). And when speaking about all manner of subjects, the president likes to make up stories filled with dramatic but fictional details. […] First, the president’s uncle died in 1985. Kaczynski was publicly revealed as the Unabomber more than a decade later, in 1996, when he was captured; before that, he had lived as a recluse in the Montana wilderness.

   2. (history) A period of ten days, particularly those in the ancient Egyptian, Coptic, and French Revolutionary calendars. [from 18th c.]
      • 2002, Colin Jones, The Great Nation, Penguin, published 2003, page 481:

        The year was divided up into twelve months renamed after the seasons [...]; each month comprised three ‘decades’ of ten days – with the décadi replacing Sundays as a day of rest; and each day was reconsecrated to a natural product or farming tool or technique.

   3. (literary, archaic) A work in ten parts or books, particularly such divisions of Livy's History of Rome. [from 15th c.]
   4. (Roman Catholicism) A series of prayers counted on a rosary, typically consisting of an Our Father, followed by ten Hail Marys, and concluding with a Glory Be and sometimes the Fatima Prayer.
   5. Any of the sets of ten sequential braille characters with predictable patterns.
   6. (electronics) A set of ten electronic devices used to represent digits.
2. (electronics) A set of resistors, capacitors, etc. connected so as to provide even increments between one and ten times a base electrical resistance.
3. (physics, engineering) The interval between any two quantities having a ratio of 10 to 1.

   There are decades between 1.8 and 18, between 25 and 250 and between 0.03 and 0.003.

使用する際の注意点

Although a decade may refer to any group of ten years, it often particularly refers to the informal ten-year periods of the calendar whose last digits run from 0 to 9. Some style guides may prefer that decade refers exclusively to such calendar periods while decennium, decennary, etc. refers to ten-year periods in other contexts. Similarly, a quinquennium etc. may be any five-year period, whereas pentad and quintade are used for the two halves of a calendrical decade.

It should be noted that the method of computing a decade is distinguished from the proper computation of centuries and millennia, which run from 1 to 0. The 1st century began with the year 1 and ended with the year 100, but "the Nineties" are the years whose name includes the word ninety, from '90 to '99, all the years of a century with a 9 as their tens place digit.

同意語

• (10 year period): decennium, decennary, decenniad, decennial

等位語

• (group) monad, duad/dyad, triad, tetrad, pentad, hexad, hebdomad/heptad, ogdoad/octad, ennead/nonad, decad/decade, hendecad, dodecad/duodecade, chiliad

派生語

関連する語

• decadal

参考

Further reading

• “decade, n.”, in OED Online ⁠, Oxford: Oxford University Press, 1894.

アナグラム

• deaced

参照

• "decade", in Charles du Fresne du Cange, Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)