• (RP) IPA: /ˈnəʊmɒn/, /-mən/
• (GA) IPA: /ˈnoʊmɑn/, /-mən/

gnomon (plural gnomons)

1. An object#Noun|object such as a pillar or a rod that is used to tell#Verb|tell time#Noun|time by the shadow#Noun|shadow it cast#Verb|casts when the sun#Noun|sun shine#Verb|shines on it, especially the pointer on a sundial. [from mid 16th c.]

   Synonyms: cock, style

2. An object such as a pillar used by an observer to calculate the meridian altitude of the sun (that is, the altitude of the sun when it reach#Verb|reaches the observer's meridian), for the purpose of determining the observer's latitude.
3. The index#Noun|index of the hour circle of a globe.
   • 1809, William Nicholson, “{smallcaps ↗”, in The British Encyclopedia, or Dictionary of Arts and Sciences; […], volume (please specify ), London: Printed by C[harles] Whittingham, […]; for Longman, Hurst, Rees, and Orme, […], OCLC 978021632 ↗, column 2:

4. (geometry) A plane#Adjective|plane figure#Noun|figure form#Verb|formed by remove#Verb|removing a parallelogram from a corner#Noun|corner of a larger parallelogram.
   • 1728, E[phraim] Chambers, “Gnomon”, in Cyclopædia: Or, An Universal Dictionary of Arts and Sciences; […] In Two Volumes, volume II (I–Z), London: Printed for James and John Knapton [et al.], OCLC 49347394 ↗, page 164 ↗, column 2:

     If a Parallelogram be divided into four leſſer ones, by two Lines interſecting each other; and one of theſe Parallelograms be retrench'd, or taken away; the other three will make a Gnomon, ordinarily call'd a Square.

5. (mathematics, by extension) A number#Noun|number representing the increment#Noun|increment between two figurate number.

• gnomonic
• gnomonics

• French: gnomon, style
• German: Gnomon
• Italian: gnomone, stilo
• Portuguese: gnômon
• Russian: гномо́н
• Spanish: estilo

• French: gnomon