Phanerozoic

adjective

Phan·​er·​o·​zo·​ic ˌfa-nə-rə-ˈzō-ik How to pronounce Phanerozoic (audio)
: of, relating to, or being an eon of geologic history that comprises the Paleozoic, Mesozoic, and Cenozoic or the corresponding systems of rocks see Geologic Time Table
Phanerozoic noun

Examples of Phanerozoic in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
One clue scientists can search for is whether a planet is in a Phanerozoic stage, which would allow a planet to host large and complex life forms. —Michael Lee, Fox News, 18 Nov. 2023

Word History

Etymology

Greek phanerós "visible, conspicuous" (from phan-, base of phaínomai, phaínesthai "to become visible, come to light, appear" + -eros, adjective suffix) + -o- + -zoic entry 2 — more at fantasy entry 1

Note: The term was introduced by the American geologist George Halcott Chadwick (1876-1953) in "Subdivision of Geologic Time," Bulletin of the Geological Society of America, vol. 41 (1930), pp. 47-48. The name refers to the easily visible fossil records that appear in this eon, in contrast to the earlier period, which Chadwick referred to collectively as the Cryptozoic (see crypto-, -zoic entry 2).

First Known Use

1930, in the meaning defined above

Time Traveler
The first known use of Phanerozoic was in 1930

Rhymes for Phanerozoic

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Browse Nearby Words

phaneroscopy
Phanerozoic
phanerozonate
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Cite this Entry

“Phanerozoic.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Phanerozoic. Accessed 30 Oct. 2025.

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Kids Definition

Phanerozoic

adjective
Phan·​er·​o·​zo·​ic ˌfan-ə-rə-ˈzō-ik How to pronounce Phanerozoic (audio)
: of, relating to, or being an eon of geological history that is made up of the Paleozoic, Mesozoic, and Cenozoic eras or the corresponding systems of rocks see geologic time
Phanerozoic noun
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