gno·​mon | \ ˈnō-mən How to pronounce gnomon (audio) , -ˌmän\

Definition of gnomon

1 : an object that by the position or length of its shadow serves as an indicator especially of the hour of the day: such as
a : the pin of a sundial
b : a column or shaft erected perpendicular to the horizon
2 : the remainder of a parallelogram after the removal of a similar parallelogram containing one of its corners

Illustration of gnomon

Illustration of gnomon

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Examples of gnomon in a Sentence

Recent Examples on the Web

There are many types of sundials, but in general each consists of a gnomon, a thin rod that casts a shadow onto a dial, and a flat plate or platform. Megan Arnett, Scientific American, "It's About Time... to Make a Sundial!," 15 Mar. 2018 The original clock is missing its gnomon, the part of a sundial that casts a shadow, but an 18th-century museum curator described it having one in the shape of a pig’s tail, so Parslow re-created that, too. National Geographic, "Ancient Sundial Shaped Like Ham Was Roman Pocket Watch," 19 Jan. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'gnomon.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of gnomon

1546, in the meaning defined at sense 1

History and Etymology for gnomon

borrowed from Latin gnōmōn "pointer of a sundial," borrowed from Greek gnṓmōn "examiner, interpreter, carpenter's square, pointer of a sundial," from gnō-, base of gignṓskein "to perceive, know" + -mon-, -mōn, agent suffix — more at know entry 1

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The first known use of gnomon was in 1546

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