from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. An object, such as the style of a sundial, that projects a shadow used as an indicator.
  • n. The geometric figure that remains after a parallelogram has been removed from a similar but larger parallelogram with which it shares a corner.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The pointer on a sundial.
  • n. A plane figure formed by removing a parallelogram from a corner of a larger parallelogram.

from the GNU version of the Collaborative International Dictionary of English

  • n. The style or pin, which by its shadow, shows the hour of the day. It is usually set parallel to the earth's axis.
  • n. A style or column erected perpendicularly to the horizon, formerly used in astronomocal observations. Its principal use was to find the altitude of the sun by measuring the length of its shadow.
  • n. The space included between the boundary lines of two similar parallelograms, the one within the other, with an angle in common. The parallelogram bf is the complement of the parallelogram df.
  • n. The index of the hour circle of a globe.

from The Century Dictionary and Cyclopedia

  • n. On a sun-dial, the triangular projecting piece which by its shadow shows the hour of the day; also, any index to a sun-dial or to a meridian-mark, especially a very large one. The early gnomons used for astronomical purposes were vertical pillars or obelisks.
  • n. The index of the hour-circle of a globe.
  • n. A piece of a parallelogram left after a similar parallelogram has been removed from a corner of it. Thus, in the figure, EFGBCD is a gnomon.
  • n. An odd number; one of the terms of an arithmetical series by which polygonal numbers are found. Also called gnomonic number.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. indicator provided by the stationary arm whose shadow indicates the time on the sundial


Latin gnōmōn, from Greek, interpreter, pointer of a sundial, from gignōskein, to know.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin gnomon, from Ancient Greek γνώμων (gnōmōn, "indicator"), related to γιγνώσκω (gignōskō, "I know") and γνῶσις (gnōsis, "knowledge"). (Wiktionary)


  • Scholars have talked, indeed, of a Greek origin or of an Etruscan origin, and the technical term for the Roman surveying instrument, _groma_, has been explained as the Greek word 'gnomon', borrowed through an

    Ancient Town-Planning

  • Nelson informed everyone that the piece sticking up was called the gnomon.

    The New Yorker Stories

  • This particular one is called a gnomon magic square, because clusters of any four contiguous numbers add up to the same sum.

    The Art Thief

  • It had always sounded strangely in my ears, like the word gnomon in the Euclid and the word simony in the


  • It had always sounded strangely in my ears, like the word gnomon in the Euclid and the word simony in the Catechism.


  • The gnomon is pierced with the letters I. C., and the arms of Mr. Conduitt, the owner, as granted to him in 1717, are engraved on the plate with his motto: "Cada uno es hijo de sus obras."

    The Book of Sun-Dials

  • The gnomons of horizontal dials are often finely designed, but to meet with such work in a vertical gnomon is rare.

    The Book of Sun-Dials

  • The gnomon is an iron rod pointing from the north pole.

    The Book of Sun-Dials

  • The obscure name I revere the most is gnomon, which is the upright part of a sundial that casts the shadow.

    Dear Clusterflock | clusterflock

  • On this device, the hour markers are on the cylinder and the gnomon is the horizontal brass arm.

    Artifacts from the Age of Astronomy


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  • A time standstill.

    October 10, 2008

  • Also, the L-shaped thing left over when you remove a square from the corner of a square. Used extensively in Euclidean geometry. The g is pronounced.

    August 16, 2008