Definition of gnomon in English:

gnomon

Line breaks: gnomon
Pronunciation: /ˈnəʊmɒn
 
/

noun

  • 1The projecting piece on a sundial that shows the time by the position of its shadow.
    More example sentences
    • The problem is that the gardeners have been caught on the gnomon of their own sundial.
    • He also probably introduced the gnomon (a perpendicular sun-dial) into Greece and erected one in Sparta.
    • He placed a pole perfectly upright in the ground to make a simple sundial, or gnomon.
  • 1.1 Astronomy A structure, especially a column, used in observing the sun’s meridian altitude.
    More example sentences
    • The simplest astronomical instruments was the gnomon, nothing other than a stick which was erected and the length of its shadow measured.
    • He is also said to have constructed a armillary sphere, a water clock, and a bronze gnomon, a pointer whose shadow gives the time of mid-day.
    • Pergolas, open steel stairs, lattices and wooden blinds all act as shadow-casters and gnomons.
  • 2 Geometry The part of a parallelogram left when a similar parallelogram has been taken from its corner.
    More example sentences
    • Revolve the gnomon about its vertex and it can draw a circle; combine two gnomons and they form a square.
    • When the gnomon is turned up, it can measure height; when it is turned over, it can measure depth and when it lies horizontally it can measure distance.

Derivatives

gnomonic

Pronunciation: /-ˈmɒnɪk/
adjective
More example sentences
  • Loxodromes appear as straight lines on the Mercator projection, while orthodromes appear as straight lines on the gnomonic projection.
  • The videos were projected onto two screens built to replicate the gnomonic and ‘Robinson projections’ of representing the globe on a two dimensional surface.
  • A gnomonic image, meanwhile, tends to make the surface appear flat, and is used by navigators and aviators in determining the shortest distance between two points.

Origin

mid 16th century: via Latin from Greek gnōmōn 'indicator, carpenter's square' (related to gignōskein 'know').

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Pronunciation: ˌastrə(ʊ)ˈgeɪʃ(ə)n
noun
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