fossil

1 of 2

adjective

fos·​sil ˈfä-səl 

1

: preserved from a past geologic age

fossil plants

fossil water in an underground reservoir

2

: being or resembling a fossil

3

: of or relating to fossil fuel

fossil energy sources

fossil

2 of 2

noun

1

: a remnant, impression, or trace of an organism of past geologic ages that has been preserved in the earth's crust compare living fossil

2

a

: a person whose views are outmoded : fogy

b

: something (such as a theory) that has become rigidly fixed

3

: an old word or word element preserved only by idiom (such as fro in to and fro)

Did you know?

A remnant, impression, or trace of an animal or plant of a past geologic age that has been preserved in the earth’s crust is called a fossil. Data from fossils are the primary source of information about the history of life on the earth. Only a small fraction of ancient organisms are preserved as fossils, and usually only organisms that have a solid skeleton or shell. Unaltered hard parts, such as the shells of clams, are relatively common in sedimentary rocks. The embedding of insects in amber and the preservation of mammoths in ice are rare but striking examples of the fossil preservation of soft tissues. Traces of organisms such as tracks and trails may also be preserved.

Synonyms of fossil

Noun

• conservative
• veteran
• fogy
• mossback
• stuffed shirt

Examples of fossil in a Sentence

Noun

some old fossil who thinks that a boy and a girl shouldn't be together unsupervised until they are engaged

Recent Examples on the Web

Adjective

Burke, who was reconstructing fossil gharials for his doctoral project, noted the subtle differences between the unidentified species and the false gharial, and started to work on an up-to-date description in December 2023. — Taylor Nicioli, CNN Money, 6 Oct. 2026

This clean hydrogen can replace fossil gas in several hard-to-abate industrial operations. — Aman Tripathi, Interesting Engineering, 23 Sep. 2026

Noun

The Mokattam Formation in northern Egypt is a thick layer of limestone that has preserved prehistoric marine fossils, including fish, sharks and early whales. — Taylor Nicioli, CNN Money, 6 Oct. 2026

The City of Boulder and Boulder County, Colorado, in 2018 sued major fossil-fuel producers Exxon Mobil and Suncor Energy, seeking financial damages under state public nuisance law. — ABC News, 5 Oct. 2026

Word History

Etymology

Adjective

earlier, "dug from the earth, preserved in the ground," borrowed from French & Latin; French fossile, borrowed from Latin fossilis "obtained by digging," from fodiō, fodere "to prod, jab, dig, remove by digging" (going back to Indo-European *b^hed^h-, *b^hod^h- "jab, dig," whence also Lithuanian bedù, bèsti "to stick, dig," Old Church Slavic bodǫ, bosti "to prick, stab," Hittite paddai "digs") + -tilis "produced by, characterized by (the action of the verb)"

Noun

derivative of fossil entry 1, or borrowed directly from Latin fossilis

First Known Use

Adjective

1665, in the meaning defined at sense 1

Noun

1736, in the meaning defined at sense 1

Phrases Containing fossil

• fossil fuel
• index fossil
• living fossil
• trace fossil

Rhymes for fossil

• docile
• jostle
• apostle
• colossal
• nitrosyl
• hypoglossal
• nannofossil

Kids Definition

fossil

1 of 2 adjective

fos·​sil ˈfäs-əl 

: being or resembling a fossil

fossil

2 of 2 noun

1

: a trace or print or the remains of a plant or animal of a past age preserved in earth or rock

2

a

: a person whose ideas are out-of-date

b

: something that has become fixed and cannot be changed