gnomon
(ˈnəʊmən)
Also 6–7 (Florio, pseudo-etymologically) gnow-, know-man, 7, 9 erron. gnomen.
[a. Gr. γνώµων inspector, indicator (spec. the gnomon of a dial, a carpenter's square), f. γνω-, γιγνώσκειν to perceive, judge, know. The proximate source may have been L. or F. gnomon.]
1. A pillar, rod, or other object which serves to indicate the time of day by casting its shadow upon a marked surface; esp. the pin or triangular plate used for this purpose in an ordinary sun-dial.
| 1546 Langley Pol. Verg. De Invent. ii. v. 42 b, Anaximenes..founde..the first dial that declareth the houres by the Shadowe of the Gnomon. 1598 Florio, Gnomone, the know-man or gnow-man of a diall. 1601 Holland Pliny I. 150 In all the circumference of this climat and parellele, at noon tide vpon an Equinoctiall day, the stile in the diall which they call Gnomon 7 foot long, casteth a shadow not aboue 4 foot. 1646 Sir T. Browne Pseud. Ep. iv. ii. 181 We usually say a Gnomon or needle is in the middle of a Diall. 1742 Young Nt. Th. ii. 427 Warnings point out our danger; Gnomons, time. 1834 H. Miller Scenes & Leg. xxix. (1857) 431 On the western gable there was fixed a huge gnomon of bronze. 1860 Tyndall Glac. i. xxv. 177 Like gnomons of a vast sundial, the Aiguilles cast their fanlike shadows, [etc.]. |
b. A column or other apparatus employed in observing the meridian altitude of the sun.
| 1625 N. Carpenter Geog. Del. i. vi. (1635) 138 In the time of either Equinoctiall in some Horizontall plaine in the Sunne-shine, let there bee erected a Gnomon. 1727–41 Chambers Cycl., Gnomon, Those conversant in observation prefer the gnomon, by some called the astronomical gnomon, to the smaller quadrants. 1837–9 Hallam Hist. Lit. I. iii. i. §70. 189 The gnomon erected by Toscanelli in the cathedral at Florence..is by much the loftiest in Europe. 1854 Tomlinson Arago's Astron. 17 Anaximander..constructed at Sparta the gnomon that enabled him to observe the equinoxes and the solstices. |
† c. jocularly. The nose. Obs.
| 1583 Stanyhurst æneis, etc. (Arb.) 145 Syth mye nose owtpeaking, good syr, your lip-labor hindreth, Hardlye ye may kisse mee, where no such gnomon apeereth. [1599 B. Jonson Cynthia's Rev. v. iv, Her nose [is] the gnomon of Loues diall, that tells you how the clocke of your heart goes.] 1781 Cowper Convers. 271 The emphatic speaker dearly loves to oppose, In contact inconvenient, nose to nose, As if the gnomon on his neighbour's phiz, Touched with the magnet had attracted his. a 1803 C. L. Lewes Mem. (1805) I. 92 Giving him at the same time, a blow that demolished the gnomen of poor Roger's face. |
† 2. Occasionally applied to other instruments serving as ‘indicators’ (see quots.). Also fig. Obs.
| 1599 Broughton's Lett. viii. 28 S. Austen [is] your Index and gnomon for S. Peters place of preaching to the spirits. 1600 R. Cawdray Treas. Similies (1609) 114 The Saylers Gnomon, or rule, which is commonly called the Marriners Needle. 1755 B. Martin Mag. Arts & Sci. iii. vii. 325 Professor Richman..lost his Life by an electrical Stroke..as he was observing..the Effects of Electricity upon his Gnomon, or Electrometer. |
† 3. pl. The teeth which indicate the age of a horse, etc. (= Gr. οἱ γνώµονες). Obs. rare—1.
| 1607 Topsell Four-f. Beasts (1658) 18 An Asse and a Mule have 36 teeth..Their third and fourth teeth are called ‘gnomons’, that is ‘regulars’, because by them there is a tryed rule to know their age. |
† 4. A rule, canon of belief or action. Obs.
[So Gr. γνώµων; a transferred use of the sense ‘carpenter's square’. (In quot. 1698 perh. an error for gnome.)]
| 1626 W. Sclater Expos. 2 Thess. (1629) 203 Making Scripture my gnomon and canon. 1651 Biggs New Disp. ¶180 A nimiety of redundance of bloud is the only Gnomon in the table of directions for phlebotomy. 1660 Jer. Taylor Duct. Dubit. ii. iii. rule xiv. §10 Eunomius..affirm'd tradition of the Fathers to be the Gnomon or Canon of faith, and yet said [etc.]. 1698 [R. Ferguson] View of an Ecclesiastic 67 To spare Mens Persons when we speak of their Faults, according to the common Gnomon, Mea & Tua Persona pro Ego & Tu. |
5. Geom. The part of a parallelogram which remains after a similar parallelogram is taken away from one of its corners.
[So Gr. γνώµων, from the resemblance of the shape to a carpenter's square.]
| 1570 Billingsley Euclid ii. def. ii. 61 In euery parallelogramme, one of those parallelogrammes, which soeuer it be, which are about the diameter, together with the two supplementes, is called a Gnomon. a 1696 Scarburgh Euclid (1705) 121 Therefore the Gnomon KLM, and the square CF are equal to the Rectangle. 1838 Young Euclid ii. Def. ii. 57. |
† b. An odd number. (So called by the Pythagoreans.) Obs.
The difference between two squares being geometrically a gnomon, the name was applied in arithmetic to the differences between the squares of successive integers, i.e. to the odd numbers 3, 5, 7, 9, 11, etc.
| 1660 Stanley Hist. Philos. ix. (1701) 379/1 Odd Numbers they called Gnomons, because being added to Squares, they keep the same Figures; so Gnomons do in Geometry. |
† c. Each of the successive subtrahends (after the first) in the process of finding the square root.
| 1674 S. Jeake Arith. (1696) 194 The second number to be substracted, called a Gnomon. |
† 6. Something shaped like a carpenter's square; an L-shaped bar, etc. Obs.
| 1669 Boyle Contn. New Exp. ii. (1682) 8 GGG is the Gnomon fastened to the plate BB. Ibid. 16 H is the Gnomon affixed to the Globe AA making fast the spring G. 1777 Darwin in Phil. Trans. LXVIII. 89 A gnomon of thin brass was made to stand over his nose. |
Hence ˈgnomonless a.
| 1832 Wilson in Blackw. Mag. XXXII. 133 The dial-stone..stands gnomenless. |