gnomon

See also: gnómon

English

WOTD – 19 May 2019

Etymology

The gnomon (sense 1) of this sundial in Taganrog, Rostov Oblast, Russia, is shaped like a triangular blade

A gnomon in geometry (sense 4)

Four is a figurate number as it can be represented by four dots arranged in a square. The next highest square is nine. Thus, the gnomon (sense 5) between four and nine is five (represented by the blue dots).

Borrowed from French gnomon, or directly from its etymon Latin gnōmōn, or directly from its etymon Ancient Greek γνώμων (gnṓmōn, “discerner, interpreter; carpenter’s square; gnomon of a sundial; (geometry) gnomon”), from γιγνώσκω (gignṓskō, “to be aware of; to perceive; to know”), ultimately from Proto-Indo-European *ǵneh₃- (“to know”); the word is thus related to know.

The geometry sense (sense 4) is from the resemblance of the plane figure to a carpenter’s square. Similarly, a gnomon in mathematics (sense 5) is also shaped like a carpenter’s square when depicted pictorially if the figurate numbers are squares.

Pronunciation

• (Received Pronunciation) IPA^(key): /ˈnəʊˌmɒn/, /ˈnəʊ.mən/

  • Audio (Southern England):

    (file)

• (General American) IPA^(key): /ˈnoʊˌmɑn/, /ˈnoʊ.mən/
• Rhymes: -əʊmɒn, -əʊmən, -oʊmɑn, -oʊmən
• Hyphenation: gno‧mon

Noun

gnomon (plural gnomons)

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

   Synonyms: cock, style

   • 1700, Samuel Foster, “[Projective Dialling: [...] The Ninth Tractate. Appendix.] Chap. IV. A General and Most Easie Way to Project Hour-lines upon All Kinds of Superfices without any Regard had to Their Standing, either in respect of Declination or Inclination”, in William Leybourn, compiler, Dialling, Plain, Concave, Convex, Projective, Reflective, Refractive. Shewing, how to Make All such Dials, and to Adorn Them with All Useful Furniture Relating to the Course of the Sun; […], 2nd edition, London: Printed by J. Matthews, for Awnsham and John Churchill […], →OCLC, page 83:

     Let a Gnomon, being firſt ſharpened into a Point, be ſhaped, and faſtned in ſuch wiſe, that it no way hinder either the draught of the Horizontal Line, or the Point of the ſhadow from having free access to the Dial at all times of the Year. […] Upon the Superfices of the Dial, obſerve the Point of the Shadow of the Gnomon (making a mark at it) and the Sun's Altitude, both of them at the ſame inſtant of time.

   • 1758 March, “An Account of an Ancient Astronomical Instrument, of Immense Dimensions, lately Restored to Use”, in Sylvanus Urban [pseudonym; Edward Cave], editor, The Gentleman’s Magazine, and Historical Chronicle, volume XXVIII, London: Printed by D[avid] Henry and R. Cave, […], published January 1755, →OCLC, page 99, column 1:

     The moſt celebrated gnomons, for examining the courſe of the ſun, which are exiſting at this time, have been ſuppoſed to be that in the church of St Petronio at Bologna, 89 Engliſh feet high; that of the Chartreux at Rome, about 67 feet; and that of St Sulpice at Paris, 86 feet. […] [T]he gnomon of the cathedral of that city [Florence], erected by [Paolo dal Pozzo] Toscanelli, in the courſe of the 16th century, whoſe height exceeds that of the three before-mentioned, taken all together, being near 300 Engliſh feet, and higher than our London monument by almoſt a third part.

   • 1817, Brahmegupta [i.e., Brahmagupta], Bháscara [i.e., Bhāskara I], “Shadow of a Gnomon”, in Henry Thomas Colebrooke, transl., Algebra, with Arithmetic and Mensuration, from the Sanscrit of Brahmegupta and Bháscara, London: John Murray, […], →OCLC, page 108:

     [T]he gnomon being the upright, and the shadow the side, the square-root of the sum of the squares is the hypotenuse; […]

   • 1981, R. M. Batson, V. S. Reed, R. L. Tyner, “Cartographic Procedures”, in George E. Ulrich, Carroll Ann Hodges, and William R[udolf] Muehlberger, editors, Geology of the Apollo 16 Area, Central Lunar Highlands […] (Geological Survey Professional Paper; 1048), Washington, D.C.: United States Government Printing Office, →OCLC, page 530:

     Approximate scales can be placed on near-field objects in pictures containing the gnomon by using an ellipse template. The Apollo 16 gnomon […] stands on three legs that, on a hard surface, define a circle 61.7 cm in diameter.

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 reaches the observer's meridian), for the purpose of determining the observer's latitude.
   • 1659, Joseph Moxon, “Prob[lem] XVIII. Another Way to Find the Height of the Pole by the Globe; if the Place of the Sun be Given; and also to Find the Hour of the Day, and Azimuth, and Almicantar of the Sun.”, in A Tutor to Astronomie and Geographie: Or An Easie and Speedy Way to Know the Use of Both the Globes, Cœlestial and Terrestrial. In Six Books. […], London: Printed by Joseph Moxon;  […], →OCLC, 2nd book (Shewing the Practical Use of the Globes. Applying Them to the Solution of Astronomical and Geographical Problemes.), page 56:

     This muſt be performed by help of a Spherick Gnomon, (as Blaew [Willem Janszoon Blaeu] calls it,) which is a ſmall Pin or Needle fixed perpendicularly into a ſmal Baſis with an hollow concave bottom, that it may ſtand upon the convexity of the Globe.

   • 1791, William Robertson, “Section II. Intercourse with India, from the Establishment of the Roman Dominion in Egypt, to the Conquest of that Kingdom by the Mahomedans”, in An Historical Disquisition Concerning the Knowledge which the Ancients had of India; […], London: Printed for A[ndrew] Strahan, and T[homas] Cadell […]; Edinburgh: E. Balfour, →OCLC, pages 78–79:

     In order to aſcertain the latitude of any place, the ancients obſerved the meridian altitude of the ſun, either by means of the ſhadow of a perpendicular gnomon, or by means of an aſtrolabe, from which it was eaſy to compute how many degrees and minutes the place of obſervation was diſtant from the Equator.

3. The index of the hour circle of a globe.
   • 1809, William Nicholson, “Index of a globe”, in The British Encyclopedia, or Dictionary of Arts and Sciences; […], volume III (E … I), London: Printed by C[harles] Whittingham, […]; for Longman, Hurst, Rees, and Orme, […], →OCLC, column 2:

     Index of a globe, the little style or gnomon, which being fixed on the pole of the globe, and turning round with it, points out the hours upon the hour circle.

4. (geometry) A plane figure formed by removing a parallelogram from a corner of a larger parallelogram.
   • 1728, E[phraim] Chambers, “Gnomon”, in Cyclopædia: Or, An Universal Dictionary of Arts and Sciences; […] In Two Volumes, volumes I (A–H), London: […] James and John Knapton [et al.], →OCLC, 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 representing the increment between two figurate numbers (“numbers equal to the numbers of dots in geometric figures formed of dots”).
   • 1999, Midhat J. Gazalé, “Figurate and $m$-adic Numbers”, in Gnomon: From Pharaohs to Fractals, Princeton, N.J., Chichester, West Sussex: Princeton University Press, →ISBN, pages 16 and 17:

     [page 16] The figurate number's gnomon is therefore $1+nb$ in the general case. A trivial family of numbers, those for which $b=0$, might be called linear. […] [page 17] Clearly, a figurate number of rank $n$ is equal to the sum of its first $n$ gnomons, and in particular the sum of the first $n$ odd numbers is equal to $n^{2}$.

Related terms

• gnomonic
• gnomonics
• gnomonist

 

Translations

object used to tell time by the shadow it casts when the sun shines on it

• Arabic: قياس m (qiyās)
• Armenian: գնոմոն (gnomon)
• Basque: gnomon
• Belarusian: гно́ман ? (hnóman)
• Bulgarian: гно́мон m (gnómon)
• Catalan: gnòmon m, estil (ca) m
• Chinese:

  Mandarin: 晷針 / 晷针 (guǐzhēn)

• Czech: gnómon m
• Danish: please add this translation if you can
• Dutch: gnomon (nl) m
• Estonian: gnoomon
• Finnish: gnomon (fi)
• French: gnomon (fr) m, style (fr) m
• Friulian: gnomon m, aste f
• Galician: gnomon m
• Georgian: გნომონი (gnomoni)
• German: Gnomon (de) m
• Greek: γνώμονας (el) m (gnómonas)

  Ancient: γνώμων m (gnṓmōn), κερκίς m (kerkís)

• Hebrew: גנומון ?
• Hindi: शंकुक (hi) ? (śaṅkuk)
• Hungarian: gnómon
• Icelandic: sólsproti ?
• Ido: gnomono (io)
• Irish: snáthaid f, snáthaid chlog gréine f
• Italian: gnomone (it) m, stilo (it) m
• Japanese: グノモン
• Korean: 규표(圭表) (gyupyo)
• Latvian: gnomons m
• Lithuanian: gnomonas m
• Malay: paku bayang
• Norwegian:

  Bokmål: gnomon m

• Occitan: gnomòn m
• Persian: اشاره‌گر, شاخص (fa) (šâxes)
• Polish: gnomon (pl) m
• Portuguese: gnômon m
• Russian: гно́мон (ru) m (gnómon)
• Sanskrit: नृ (sa) m (nṛ), स्थाणु (sa) m (sthāṇu)
• Serbo-Croatian:

  Cyrillic: гно̀мо̄н m

  Roman: gnòmōn (sh) m

• Slovak: gnómon m
• Slovene: gnómon ?
• Spanish: estilo (es) m
• Swedish: gnomon ?
• Turkish: gnomon
• Ukrainian: ґно́мон ? (gnómon)

object used to calculate the meridian altitude of the sun

• Friulian: gnomon m
• Romanian: gnomon (ro) n

index of the hour circle of a globe

plane figure formed by removing a parallelogram from a corner of a larger parallelogram

• French: gnomon (fr) m
• Friulian: gnomon m
• Hungarian: gnómon
• Slovene: gnomon ?
• Urdu: علم (ur) m

number representing the increment between two figurate numbers

Further reading

• gnomon on Wikipedia.Wikipedia
• gnomon (figure) on Wikipedia.Wikipedia
• gnomon (disambiguation) on Wikipedia.Wikipedia
• “gnomon”, in The Century Dictionary […], New York, N.Y.: The Century Co., 1911, →OCLC.
• “gnomon”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.
• “gnomon”, in OneLook Dictionary Search.
• “gnomon”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.

Dutch

Pronunciation

• Audio:

  (file)

Noun

gnomon m (plural gnomons)

1. gnomon

Related terms

• zonnewijzer

 

Further reading

• “gnomon” in Woordenlijst Nederlandse Taal – Officiële Spelling, Nederlandse Taalunie. [the official spelling word list for the Dutch language]

Esperanto

Pronunciation

• IPA^(key): [ˈɡnomon]
• Rhymes: -omon
• Hyphenation: gno‧mon

Noun

gnomon

1. accusative singular of gnomo

French

Etymology

Borrowed from Latin gnōmōn, from Ancient Greek γνώμων (gnṓmōn, “indicator”).

Pronunciation

• IPA^(key): /ɡnɔ.mɔ̃/

• Audio:

  (file)

Noun

gnomon

1. gnomon

Related terms

• gnomonique

 

Further reading

• “gnomon”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012.

Latin

gnōmōn (rod on a sundial)

Etymology

Borrowed from Ancient Greek γνώμων (gnṓmōn, “discerner, interpreter; gnomon of a sundial”), from γιγνώσκω (gignṓskō, “to be aware of; to perceive; to know”), ultimately from Proto-Indo-European *ǵneh₃- (“to know”).

Pronunciation

• (Classical Latin) IPA^(key): /ˈɡnoː.moːn/, [ˈŋnoːmoːn]
• (modern Italianate Ecclesiastical) IPA^(key): /ˈɲo.mon/, [ˈɲɔːmon]

Noun

gnōmōn m (genitive gnōmonis); third declension

1. gnomon; rod or pillar on a sundial whose shadow is used to indicate the time

Declension

Third-declension noun.

	singular	plural
nominative	gnōmōn	gnōmonēs
genitive	gnōmonis	gnōmonum
dative	gnōmonī	gnōmonibus
accusative	gnōmonem	gnōmonēs
ablative	gnōmone	gnōmonibus
vocative	gnōmōn	gnōmonēs

Derived terms

• gnōmonicē
• gnōmonicus

 

Descendants

All borrowed

• Catalan: gnòmon
• English: gnomon
• French: gnomon
• Italian: gnomone
• Portuguese: gnômon
• Romanian: gnomon
• Spanish: gnomon

References

• “gnomon”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• gnomon in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.

Polish

Pronunciation

• IPA^(key): /ˈɡnɔ.mɔn/

• Audio:

  (file)

• Rhymes: -ɔmɔn
• Syllabification: gno‧mon

Noun

gnomon m inan

1. gnomon

Declension

Declension of gnomon

	singular	plural
nominative	gnomon	gnomony
genitive	gnomonu	gnomonów
dative	gnomonowi	gnomonom
accusative	gnomon	gnomony
instrumental	gnomonem	gnomonami
locative	gnomonie	gnomonach
vocative	gnomonie	gnomony

Related terms

adjective

• gnomoniczny

 

noun

• gnomonika

 

Further reading

• gnomon in Wielki słownik języka polskiego, Instytut Języka Polskiego PAN
• gnomon in Polish dictionaries at PWN

Romanian

Etymology

Borrowed from French gnomon or Latin gnomon.

Pronunciation

• IPA^(key): /ɡnoˈmon/

Noun

gnomon n (plural gnomoane)

1. gnomon

Declension

	singular			plural
	indefinite	definite		indefinite	definite
nominative-accusative	gnomon	gnomonul		gnomoane	gnomoanele
genitive-dative	gnomon	gnomonului		gnomoane	gnomoanelor
vocative	gnomonule			gnomoanelor

Related terms

• gnomonic
• gnomonică

 

Further reading

• gnomon in DEX online—Dicționare ale limbii române (Dictionaries of the Romanian language)

Swedish

Noun

gnomon ?

1. gnomon

Declension

This noun needs an inflection-table template.

Related terms

• gnomonik
• gnomonisk

 

Further reading

• gnomon in Svensk ordbok.