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 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

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'Phanerozoic.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

Dictionary Entries Near Phanerozoic

Cite this Entry

“Phanerozoic.” Dictionary, Merriam-Webster, Accessed 18 Apr. 2024.

Kids Definition


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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