gradientadj.n.
/ˈɡreɪdɪənt/, U.S. /ˈɡreɪdiənt/ A. adj.
1.
a. Of animals: Characterized by taking steps with the feet, as their distinctive mode of progression; walking, ambulant.
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the world > animals > by locomotion > [adjective] > adapted for walking
ambulatory1648
gradient1648
gressorial1842
1648 Bp. J. Wilkins Math. Magick ii. iv. 174 Amongst these gradient Automata, that iron spider mentioned in Walchius is more especially remarkable.
1663 R. Boyle Some Considerations Usefulnesse Exper. Nat. Philos. i. ii. 40 But it is not so conspicuous in gradient animals (if I may so speak) as in swimming ones.
1668 Bp. J. Wilkins Ess. Real Char. 161 Oviparous Beasts..Gradient; having four feet.
1822 T. Taylor tr. Apuleius Metamorphosis 300 There are animals adapted to the several parts, the volant living in the air, and the gradient on the earth.
b. Heraldry. Said of a tortoise depicted as walking.
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society > communication > indication > insignia > heraldic devices collective > heraldic representations of creatures > [adjective] > specific movements of heraldic beasts > of tortoise
gradient1780
1780 J. Edmondson Compl. Body Heraldry II. (Gloss.) Gradient, an heraldic term applied to a tortoise supposed walking.
1828–40 W. Berry Encycl. Her. I.
2. Of a railway line: Rising or descending by regular degrees of inclination. rare. (? A figment, apparently only attested in dictionaries or glossaries.)
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1855 in J. Ogilvie Imperial Dict. Suppl. Hence in mod. Dicts.
B. n.
1. figurative.1868 W. H. Dixon Spiritual Wives I. xv. 159 That duality in the soul of nature..led by an easy gradient into a state of manners, as between brother and sister, which [etc.].
a. Of a road or railway: Amount of inclination to the horizontal; degree of slope; = grade n. 10.This sense can hardly have been evolved from that of the Latin participle or the English adjective; possibly it was a new formation on grade, after the supposed analogy of quotient.
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society > travel > means of travel > route or way > way, path, or track > road > parts of road > [noun] > inclined portion of road, etc. > degree of slope
gradient1835
1835 Railway Mag. Dec. 264 The line of Railroad here proposed..passing over the most easy and beautiful tract of country..with the most favourable gradients.
1836 Dublin Rev. May 225 In describing the gradients of a railway, it is usual to state the rise per mile in feet.
1836 Mechanics' Mag. 6 Aug. 317 In a contemporary journal there appears a violent tirade against the word gradient as at present used by civil engineers.
1861 S. Smiles Lives Engineers II. 429 One in thirty being about the severest gradient at any part of the road.
1868 W. Peard Pract. Water-farming xi. 111 Wherever they have been constructed on a gradient of 1 in 9..they have answered admirably.
1880 S. Haughton Six Lect. Physical Geogr. v. 241 The uniformly increasing gradient with which the pampas everywhere rise.
1884 American 8 86 The road was built with needlessly steep gradients.
b. A part of a road which slopes upward or downward; a portion of a way not level.
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society > travel > means of travel > route or way > way, path, or track > road > parts of road > [noun] > inclined portion of road, etc.
grade1811
gradient1845
downgrade1847
1845 Rep. Brit. Assoc. 1844 ii. 96 It was necessary that that railway should present long and very steep gradients.
1915 R. B. Holt Tramway Track Constr. & Maintenance ix. 114 The wear on the rails on all parts of the gradient, both on the up track and on the down track, is exceedingly irregular.
1971 Homes & Gardens Aug. 90/1 The train..could be heard puffing like an old man, ‘Chuff, chuff, chuff’, as it travelled up the gradient approaching the cutting.
1971 Daily Tel. 27 Aug. (Colour Suppl.) 12/3 Snow drove into our faces and on the steep gradients where skis had to be removed we stumbled in deep powder.
2.
a. transferred. Originally: the proportional amount of rise or fall of the barometer or thermometer in passing from one region to another. Now in wider use: a continuous increase or decrease in the magnitude of any quantity or property along a line from one point to another; also, the rate of this change, expressed as the change in magnitude per unit change in distance.The ‘barometric gradient’ is expressed in hundredths of an inch to a degree of a great circle; thus ‘a gradient of 4 means that over a distance of 60 nautical miles, the barometer rises 4/ 100 or 1/ 25 of an inch’ (Huxley Physiogr. 95).
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the world > time > change > change to something else, transformation > gradual change > [noun] > in magnitude
gradient1870
the world > the earth > weather and the atmosphere > weather > study or science of weather > meteorological instruments > [noun] > barometer > height of mercury in > (proportional) rise and fall
variation1719
gradient1870
1870 J. D. Everett Deschanel's Elem. Treat. Nat. Philos. I. xiii. 168 Generally speaking, the wind blows from regions of high to regions of low barometer, and with greater force as the barometric gradient is steeper.
1876 P. G. Tait Lect. Recent Adv. in Physical Sci. xi. 263 The temperature will fall off by a uniform gradient.
1878 T. H. Huxley Physiography (ed. 2) 95 If the isobars run close together it shows that the gradient is high, and therefore the winds will be strong.
1880 Times 11 Aug. 11/6 Gradients for westerly winds lay over Scotland, and for easterly winds over the Bay of Biscay.
1882 E. D. Archibald in Nature 4 May 11/2 The primary cause of cyclones, according to Ferrel, is a horizontal temperature gradient.
1886 J. A. Fleming Short Lect. Electr. Artisans vii. 122 Along the lead there is a regular fall or gradient of [electrical] pressure.
1892 W. Peddie Man. Physics ix. 132 The rate of variation of density per unit of length is r... The quantity r is generally called the ‘concentration-gradient’.
1898 Proc. Royal Soc. 63 364 The kathode fall is constant for all pressures and currents whilst the potential gradient along the rest of the tube is variable.
1902 J. H. Poynting & J. J. Thomson Text-bk. Physics: Properties of Matter xviii. 205 The ratio of the stress to the velocity gradient is called the viscosity of the fluid.
1910 Encycl. Brit. V. 891/2 This outflow of heat necessitates a rise of temperature with increase of depth. The corresponding gradient is of the order of 1°C. in 100 ft.
1948 S. Glasstone Textbk. Physical Chem. (ed. 2) iv. 260 The gradient is actually negative, that is the concentration decreases from left to right.
1957 Encycl. Brit. X. 681/2 He proposed to measure the rate of change or gradients in the gravitational field.
1962 A. R. W. Hayes Revision Physics 98 We must measure..the uniform temperature gradient along the bar—found from readings of thermometers placed in mercury..in holes bored in the specimen.
1970 Nature 19 Dec. 1225/1 There is a gradient of dormancy within the spikelet, the larger proximal seed being less dormant than the smaller distal seed, while a much smaller third seed..is extremely dormant.
b. spec. in Embryology, such an increase or decrease, along an axis of an organism or a part, in the potential for developing into an organ or in a related bodily process.
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the world > life > biology > biological processes > metabolism > [noun] > change in
gradient1911
afterburn1988
1911 C. M. Child in Jrnl. Exper. Zool. XI. 214 These facts..show very clearly that an axial gradient exists in a large number of organisms and that in many cases at least the apical or anterior region is dominant in regulation.
1915 C. M. Child Individuality in Organisms iii. 65 Gradients in rate of cell division, size of cells, condition or amount of protoplasm in the cells, rate of growth, and rate and sequence of differentiation are very characteristic features of both animal and plant development. Such gradients are definitely related to the axes of the individual or its parts, and are..expressions of axial metabolic gradients.
1924 Bellamy & Child in Proc. Royal Soc. B. 96 141 In a protoplasm of specific hereditary constitution, such a gradient is adequate as the initiating factor in the axial differentiation characteristic of that species.
1927 G. R. de Beer in Biol. Rev. Mar. 189 The only hypothesis which appears tenable is that of a Gradient System or ‘field’..for the place of determination of the rudiments of other organs.
1953 J. S. Huxley Evol. in Action i. 29 Gradients exist in the developing organism—gradients in metabolism, growth-potential, and other factors. Genes altering the shape and intensity of such gradients will affect a number of parts simultaneously.
1957 Encycl. Brit. VIII. 976/2 Each area or morphogenetic field..is a gradient field in the sense that the capacity for differentiation is highest in the centre and diminishes gradually toward the periphery.
1970 F. Crick in Nature 31 Jan. 420/1 It is an old idea that ‘gradients’ are involved in embryological development... Many of the gradients to which Child referred seem more likely, in retrospect, to be the results of development rather than its cause. An outsider to embryology has the impression that in recent years gradients have become a dirty word.
1970 F. Crick in Nature 31 Jan. 422/1 If this approach serves to make the idea of diffusion gradients respectable to embryologists it will have served its purpose.
3. Mathematics. A rational integral function of a number of quantics of assigned weights, which is of one degree and one weight throughout (Prof. Elliott).
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the world > relative properties > number > algebra > [noun] > expression > function
function1758
exponential1784
potential function1828
syzygy1850
permutant1852
Green function1863
theta-function1871
Greenian1876
Gudermannian1876
discriminoid1877
Weierstrassian function1878
gradient1887
beta function1888
distribution function1889
Riemann zeta function1899
Airy integral1903
Poisson bracket1904
Stirling approximation1908
functional1915
metric1921
Fourier transform1923
recursive function1934
utility function1934
Airy function1939
transfer function1948
objective function1949
restriction1949
multifunction1954
restriction mapping1956
scalar function1956
Langevin function1960
mass function1961
1887 J. J. Sylvester in Amer. Jrnl. Math. 9 2 A rational intergral homogeneous and isobaric function (or, to avoid a tedious periphrasis, say a gradient).
1895 E. B. Elliott Algebra of Quantics 145, 146, 233.
4. The degree of steepness of a graph at any point, measured by the tangent of the angle between the horizontal axis and either the line (if straight) or the tangent to the curve; (see also quot. 1937).
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the world > relative properties > number > graph or diagram > [noun] > graph > properties of
gradient1897
embed1922
embeddability1936
reachability1959
1897 H. Lamb Elem. Course Infinitesimal Calculus ii. 67 It is convenient to have a name for the property of a curve which is measured by the derived function. We shall use the term ‘gradient’ in this sense.
1937 E. J. McShane tr. R. Courant Diff. & Integral Calculus (ed. 2) I. xi. 90 The slope or gradient of the curve is given by tan a, and hence the term gradient is occasionally used for the derivative of the function represented by the curve.
1942 C. E. K. Mees Theory Photogr. Process xix. 702 The D, log E curve continues..into the region of decreasing exposure with constantly decreasing gradient.
1958 A. Barton Introd. Coordinate Geom. v. 64 A line whose gradient is zero is parallel to the x-axis; as the gradient increases the line gets steeper.
1958 A. Barton Introd. Coordinate Geom. v. 66 Two lines are..perpendicular if the product of their gradients is −1.
5. Mathematics. A vector function whose components along the co-ordinate axes are the partial derivatives with respect to the corresponding variables of a given scalar function; it is denoted by ∇f (see del n.) or by grad f, where f is the scalar function.
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the world > relative properties > number > mathematical number or quantity > tensor > [noun] > vector > function of
vector function1873
vector potential1873
vector product1878
gradient1901
scalar triple product1901
vector triple product1901
grad1909
1901 E. B. Wilson Vector Anal. iii. 138 The vector sum which is the resultant rate of increase of V is denoted by ∇V... The terms gradient and slope of V are..used for ∇V.
1936 E. J. McShane tr. R. Courant Diff. & Integral Calculus II. iii. 89 The direction of the gradient is the direction in which the function increases most rapidly.
1966 McGraw-Hill Encycl. Sci. & Technol. (rev. ed.) II. 413/1 There are three differentiation processes that are of conceptual value in the study of vectors: the gradient of a scalar, the divergence of a vector, and the curl of a vector.
Compounds
gradient wind n. Meteorology the (hypothetical) wind whose direction is that of the geostrophic wind but whose speed is calculated by allowing for the effect on the geostrophic wind of the centrifugal force that results from its curved path.
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1908 E. Gold Barometric Gradient & Wind Force 24 We can construct a scale..which shall give..the Beaufort number corresponding to the theoretical gradient wind for straight isobars for any pressure distribution.
1928 D. Brunt Meteorol. vii. 66 The value of the gradient wind which is derived when the curvature of the path is neglected is called the geostrophic wind.
1966 McGraw-Hill Encycl. Sci. & Technol. (rev. ed.) VI. 244/2 The gradient wind is a good approximation to the actual wind and is often superior to the geostrophic wind, particularly when the flow is strongly curved in the cyclonic sense.
This entry has not yet been fully updated (first published 1900; most recently modified version published online June 2022).
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adj.n.1648