gno·​mon ˈnō-mən How to pronounce gnomon (audio)
: an object that by the position or length of its shadow serves as an indicator especially of the hour of the day: such as
: the pin of a sundial
: a column or shaft erected perpendicular to the horizon
: the remainder of a parallelogram after the removal of a similar parallelogram containing one of its corners

Illustration of gnomon

Illustration of gnomon
  • bcdefg gnomon 2

Examples of gnomon in a Sentence

Recent Examples on the Web The gnomon, or the shadow-casting protrusion, is 35 feet tall with a shadow twice that length. Stefanie Waldek, Travel + Leisure, 15 Nov. 2021 But the most original marketing device was a giant sundial, its vertical monument (called a gnomon) 28 feet long and 17 feet high and standing in a circle 34 feet in diameter. Gary Kamiya, San Francisco Chronicle, 9 July 2021 The pole serves as a gnomon, the part of a sundial that casts a shadow to denote time. Jeanne Huber, Washington Post, 20 Apr. 2020 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, 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, 19 Jan. 2017

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

Word History


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

First Known Use

1546, in the meaning defined at sense 1

Time Traveler
The first known use of gnomon was in 1546

Dictionary Entries Near gnomon

Cite this Entry

“Gnomon.” Dictionary, Merriam-Webster, Accessed 25 Feb. 2024.

Kids Definition


gno·​mon ˈnō-mən How to pronounce gnomon (audio)
: an object (as on a sundial) that by the position or length of its shadow serves to indicate the hour of the day
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