Skip to main content
Select Source:

eon

eon
1. The largest geologic-time unit, incorporating a number of eras. The equivalent chronostratigraphic unit is the (little used) eonothem. Originally, two eons were proposed in 1930 by G. H. Chadwick. The younger was the Phanerozoic Eon (the time of evident life), comprising the Cenozoic, Mesozoic, and Palaeozoic Eras, and this term is still used. The term suggested for the preceding eon was the Cryptozoic (the time of hidden life). This time has also been called the Archaeozoic (the time of most ancient life), but most commonly has been known simply as the Precambrian. Three eons have been proposed for Precambrian time: the Priscoan for time before 4000 Ma ago; the Archaean for 4000–2500 Ma ago; and the Proterozoic for 2500–590 Ma ago; the term ‘Precambrian’ is still in frequent use but is informal.

2. A time unit of 109 present Earth years.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"eon." A Dictionary of Ecology. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"eon." A Dictionary of Ecology. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/eon-0

"eon." A Dictionary of Ecology. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/eon-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

eon

eon
1. The largest geologic-time unit, incorporating a number of eras. The equivalent chronostratigraphic unit is the eonothem. Originally, two eons were proposed in 1930 by G. H. Chadwick. The younger was the Phanerozoic Eon (time of evident life), comprising the Cenozoic, Mesozoic, and Palaeozoic Eras, and this term is still used. The term suggested for the preceding eon was the Cryptozoic (time of hidden life). This time has also been called the Archaeozoic (time of most ancient life), but most commonly has been known simply as the Precambrian. Three eons have been proposed for Precambrian time: the Priscoan for time before 4000 Ma ago; the Archaean for 4000–2500 Ma ago; and the Proterozoic for 2500–590 Ma ago; the term ‘Precambrian’ is still in frequent use but is informal.

2. A time unit of 109 present Earth years.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"eon." A Dictionary of Earth Sciences. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"eon." A Dictionary of Earth Sciences. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/eon

"eon." A Dictionary of Earth Sciences. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/eon

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

eon

e·on / ˈēən; ˈēˌän/ (chiefly Brit. also ae·on) • n. (often eons) an indefinite and very long period of time, often a period exaggerated for humorous or rhetorical effect: he reached the crag eons before I arrived. ∎  Astron. & Geol. a unit of time equal to a billion years. ∎ Geol. a major division of geological time, subdivided into eras: the Precambrian eon. ∎  Philos. (in Neoplatonism, Platonism, and Gnosticism) a power existing from eternity; an emanation or phase of the supreme deity.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"eon." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"eon." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/eon-0

"eon." The Oxford Pocket Dictionary of Current English. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/eon-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

eon

eon see AEON.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"eon." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"eon." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/eon-1

"eon." The Concise Oxford Dictionary of English Etymology. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/eon-1

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

eon

eonEritrean, Ghanaian, Himalayan, Malayan, Tigrayan •Actaeon, Aegean, aeon (US eon), Augean, Behan, Cadmean, Caribbean, Carolean, Chaldean, Cyclopean, empyrean, epicurean, European, Fijian, Galilean, Hasmonean, Hebridean, Herculean, Ian, Jacobean, Kampuchean, Laodicean, lien, Linnaean (US Linnean), Maccabean, Mandaean (US Mandean), Medicean, monogenean, Nabataean (US Nabatean), Orphean, paean, paeon, pean, peon, Periclean, piscean, plebeian, Pyrenean, Pythagorean, Sabaean, Sadducean, Sisyphean, skean, Tanzanian, Tennesseean, Terpsichorean, theodicean, Tyrolean

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"eon." Oxford Dictionary of Rhymes. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"eon." Oxford Dictionary of Rhymes. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/eon

"eon." Oxford Dictionary of Rhymes. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/eon

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.