# Definition of gnomon in English:

## gnomon

### noun

• 1The projecting piece on a sundial that shows the time by the position of its shadow.

• ‘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.’
• ‘To ensure that the sundial registered roughly the correct time all the year round the gnomon had to be set at exactly the correct angle.’
1. 1.1Astronomy A structure, especially a column, used in observing the sun's meridian altitude.
• ‘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.’
• ‘It is an astronomy text, showing how to measure the positions of the heavenly bodies using shadow gauges which are also called gnomons, but it contains important sections on mathematics.’
• ‘The text measures the positions of the heavenly bodies using shadow gauges which are also called gnomons.’
• 2Geometry
The part of a parallelogram left when a similar parallelogram has been taken from its corner.

‘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.’

### Origin

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

/ˈnəʊmɒn/