a. and sb. [ad. L. līneāris, f. līnea LINE. Cf. F. linéaire.]
A. adj.
1. Of or pertaining to a line or lines. Linear perspective: that branch of perspective that is concerned with the apparent form, magnitude and position of visual objects, as distinguished from aerial perspective (see AERIAL 4).
1656. in Blount, Glossogr.
1841. W. Spalding, Italy & It. Isl., I. 192. When backgrounds were introduced, they were ill-executed, the linear-perspective being nowhere accurately observed.
1865. Pall Mall Gaz., 11 Nov., 9. That linear hardness which never appears in nature.
1869. J. Martineau, Ess., II. 63. The general rules of linear perspective.
1878. Gurney, Crystallogr., 29. This difference between models and crystals must be remembered. The former have linear symmetry.
2. Consisting of lines; involving the use of lines.
1840. Lardner, Geom., ix. 93. The … extent of space included within the linear boundaries of any figure is called its area.
1884. Ruskin, Pleas. Eng., 21. The Celts developing peculiar gifts in linear design, but wholly incapable of drawing animals and figures.
1900. D. G. Hogarth, in Contemp. Rev., Dec., 795–6. Two systems of writing, pictographic and linear, did indeed exist in the early Ægean world.
fig. 1830. Carlyle, Misc. (1857), II. 172. Narrative is linear, Action is solid.
3. Having the direction of a line; extended in a line or in length; spec. in Math. and Phys. involving measurement in one dimension only. Linear equation, an equation of the first degree. Linear numbers, linear problem (see quot. 1706).
1706. Phillips (ed. Kersey), Linear Numbers, are those that have relation to Length only: For Example, such as represent one Side of a plane Figure; and if the Figure be a Square, the Linear Number is call’d a Root. Ibid., Linear Problem (in Mathem.), such a Problem as can be solved Geometrically, by the Intersection … of two Right-lines.
1799. J. Wood, Elem. Optics, iv. (1811), 83. This line is called the diameter, or linear aperture of the lens.
1806. Hutton, Course Math., I. 340. Similar Prisms and Cylinders are to each other, as the Cubes of their Altitudes, or of any other Like Linear Dimensions.
1812–6. Playfair, Nat. Phil. (1819), I. 201. The superficial breadth of the stream, expressed in linear inches.
1816. trans. Lacroix’s Diff. & Int. Calculus, 326. We call it from thence, a linear equation of the first order.
1830. Lyell, Princ. Geol., I. 314. Active volcanic vents … arranged in a linear direction.
1831. Brewster, Optics, xli. 336. The linear magnifying power is the number of times an object is magnified in length.
1867. Denison, Astron. without Math., 71. The resistance does diminish the actual or linear speed.
1872. Nicholson, Palæont., 44. It is possible to arrange the animals of any one sub-kingdom in something like a linear series.
1882. Minchin, Unipl. Kinemat., 6. A point P moves in a circle with constant linear velocity. Ibid., 123. So that (ξ, η) are also linear functions of (ξ′, η′); and if the first satisfy a linear equation … so must the second.
4. Resembling a line; very narrow in proportion to its length, and of uniform breadth.
1642. H. More, Song of Soul, II. I. ii. 42. [The Soul] Girds the swoln earth with linear list.
1828. Stark, Elem. Nat. Hist., I. 362. Body gray brown, with transverse linear whitish stripes.
1853. G. Bird, Urin. Deposits (ed. 3), 357. Minute linear bodies hardly so long as the diameter of a blood-corpuscle.
1854. Brewster, More Worlds, xi. 178. These linear nebulæ, which Sir John Herschel thinks are flat ellipsoids seen edgewise.
1885. Watson & Burbury, Math. Th. Electr. & Magn., I. 218. A conductor, two of whose dimensions are very small compared with the third, as for instance a wire, is called a linear conductor.
b. spec. Bot. and Zool. Like a thread, elongated.
1753. Chambers, Cycl. Supp., s.v. Leaf, Linear Leaf, one the two sides of which run almost parallel to one another.
1777. Robson, Brit. Flora, 15. Linear, everywhere of the same breadth, though sometimes narrowing at the extremities only.
1787. Fam. Plants, I. 2. Anther linear … Stigma linear.
1828. Stark, Elem. Nat. Hist., II. 89. Shell equivalve…; hinge linear, without teeth.
1851. Richardson, Geol. (1855), 180. Verticillate fringes of linear leaves growing round the joints.
1851. Woodward, Mollusca, 106. Muricidæ…. Lingual ribbon long, linear.
1870. Hooker, Stud. Flora, 225. Campanula rotundifolia,… lower cauline leaves lanceolate, upper narrow linear quite entire.
1874. Coues, Birds N. W., 430. Two narrowly linear feathers.
1880. Gray, Struct. Bot., iii. § 4 (ed. 6), 95. Linear, when leaf-blades are narrow, several times longer than wide, and of about the same breadth throughout.
c. Having a (more or less) plain outline; not indented or notched; also said of the outline.
1796. C. Marshall, Garden., xii. (1813), 139. A tree may be regular without being linear.
1797. Encycl. Brit. (ed. 3), III. 444/1. A Margin … entire, linear without the least dent or notch.
5. Surg. Linear extraction (of cataract): see quot. 1890. Linear rectotomy: the operation of dividing a strictured urethra through the rectum.
1874. G. Lawson, Dis. Eye, 127. Linear Extraction of Cataract.
1878. T. Bryant, Pract. Surg., I. 724. M. Verneuil has advocated the operation of ‘linear rectotomy’ for the cure of stricture.
1890. Billings, Nat. Med. Dict., Linear extraction, methods of cataract extraction in which the corneal incision approaches to a plane passing through the centre of curvature of the globe.
6. Comb. chiefly Bot., signifying ‘linear and …,’ ‘between linear and …,’ as linear-acute, -attenuate, -awled, -elliptical, -elongate, -ensate, -filiform, -lanceolate, -ligulate, -oblong, -obovate, -setaceous, -spathulate, -subulate adjs.; also linear-leaved, -shaped adjs.
1847. W. E. Steele, Field Bot., 9. Hawkweed,… bracts *linear-attenuate.
a. 1794. Sir W. Jones, in Asiat. Res. (1795), IV. 269. Leaves *linear-awled, pointed, opposite.
1881–2. W. S. Kent, Man. Infusoria, II. 786. Body … *linear-elliptical.
1836. Loudon, Encycl. Plants, Gloss., *Linear-ensate, long sword-shaped.
1845. Lindley, Sch. Bot., iv. (1858), 42. 1. A[lsine] rubra. Leaves *linear-filiform, mucronate, somewhat fleshy.
1793. Martyn, Lang. Bot., Lineari-lanceolatum, *linear-lanceolate.
1825. Greenhouse Comp., II. 20. Pharnaceum lineare, *linear-leaved Pharnaceum.
1870. Hooker, Stud. Flora, 373. Potamogeton…. Leaves … *linear-ligulate.
1839. Johnston, in Proc. Berw. Nat. Club, I. No. 7. 205. Teeth transverse, *linear-oblong.
1870. Hooker, Stud. Flora, 312. Rumex conglomeratus,… inner fruiting sepals linear-oblong.
1845. Florist’s Jrnl., 89. Styphelia tubiflora.… Leaves which are sometimes *linear-obovate.
1847. W. E. Steele, Field Bot., 21. Scales of receptacle *linear-setaceous.
1845. Darwin, Voy. Nat., vii. (1879), 126. The view would resemble that of a great lake, if it were not for the *linear-shaped islets.
1870. Hooker, Stud. Flora, 130. Saxifraga Andrewsii.… Leaves *linear-spathulate.
1793. Martyn, Lang. Bot., Lineari-subulatum, *linear-subulate.
b. in quasi-Latin form, as lineari-elongate, -laciniose, -oblong adjs.
1871. W. A. Leighton, Lichen-flora, 9. Spores 8, oblong or lineari-elongate or cylindrical. Ibid., 12. Spores 8, colourless, lineari-oblong or subfusiform. Ibid., 18. Fuscous-black, lineari-laciniose, laciniæ ligulate.
† B. sb. A linear equation. Obs.
1684. T. Baker, Geometr. Key, title-p., Of linears, qvadratics, cubics, biqvadratics; And the finding of all their Roots.
