[ad. L. conjugāt-us, pa. pple. of conjugāre: see prec.]
A. adj. I. Joined together, conjoined.
1. Joined together, esp. in a pair, coupled; connected, related. (In quot. 1552 = united in marriage.)
1471. Ripley, Comp. Alch., iv., in Ashm. (1652), 144. Soe be they together surely conjugate.
1552. Huloet, Bastard begotten betwene base and gentle, or betwene coniugate and single, spurius.
1605. Bacon, Adv. Learn., II. ix. § 1. Human philosophy … hath two parts; the one considereth man segregate or distributively; the other congregate, or in society. So as human philosophy is either simple and particular, or conjugate and civil.
1879. Ingleby, Shaks. Cent. Praise, 177. The conjugate use of ‘whilst’ and ‘then’ in these verses is, to say the least, very unusual.
1881. Westcott & Hort, Grk. Test. Introd., § 287. Three pairs of conjugate leaves.
2. Gram. Applied to words that are directly derived from the same root or stem, and therefore usually of kindred meaning; as wise, wisely, wisdom. [L. conjugata verba.]
1862. Marsh, Eng. Lang., i. 18. Our word language has no conjugate adjective. Ibid., xxvi. 421. Cost and costly … are strictly conjugate.
1864. Bowen, Logic, ix. 277. Another source of ambiguity is the supposition that paronymous or conjugate words—as the substantive, verb, adjective, and adverb formed from the same root—necessarily agree in meaning.
3. Chem. In conjugate compound, acid, radical: see quots.
1882. Watts, Dict. Chem., II. 8 [quoting Laurent and Gerhardt]. We designate as conjugate compounds all such as are formed by the direct union of two bodies, with elimination of water, and are capable of reproducing the original bodies by again taking up the elements of water. Ibid., 10. Another class of acids to which the term conjugate is still sometimes applied, includes those which result from a peculiar action of sulphuric acid … on certain organic bodies.
4. a. Bot. Said of leaves or (formerly) flowers that grow in pairs; spec. applied to a pinnate leaf having only one pair of leaflets.
1794. Martyn, Rousseau’s Bot., xvi. 199. The leaves are double or conjugate, that is, come out in pairs.
1835. Lindley, Introd. Bot. (1848), I. 261. The conjugate leaf of Zygophyllum.
1866. Treas. Bot., Conjugate, paired; when the petiole of a leaf bears one pair only of leaflets.
b. Anat. Conjugate foramen: a foramen or aperture at the junction of two bones, esp. vertebræ, formed by the apposition of opposite notches.
1870. Rolleston, Anim. Life, 8. For the blood to pass out … by a conjugate foramen. Ibid., 141. Two alternately placed series of conjugate foramina.
c. Biol. Said of the cells or filaments that have united in CONJUGATION (sense 5).
1843. trans. Müller’s Phys., II. 1505. In each of the conjugate filaments, some cells are the recipients, while others yield their contents to the opposite cell of the contiguous filament.
5. Path. Conjugate deviation: the forced and persistent turning of both eyes to one side while their relation to each other remains unaltered.
1882. Med. Temp. Journal, 78. There is no conjugate deviation of the eyes as often occurs in apoplexy.
1886. W. Stirling, Text-bk. Phys. (ed. 2), 849. In hemiplegia the muscles on one side are paralysed, so that the head and often the eyes are turned away from the paralysed side. This is called ‘conjugate deviation’ of the eyes, with rotation of the head and neck.
II. Joined in a reciprocal relation.
6. Physics. Applied to two points, lines, quantities, or things, which are so reciprocally related that any or every property of the first with respect to the second is also true of the second with respect to the first.
The corresponding Greek συζυγεῖς was first applied by Apollonius (Conica, I. 56) to conjugate hyperbolas.
a. Math. (Here also applied in a secondary sense to that which is conjugate to the main element, e.g., in conjugate axis, diameter, point.)
Conjugate axes or diameters (of a conic): two axes, etc., such that each is parallel to the tangent at the extremity of the other; in a conicoid, there are three conjugate diameters. Conjugate axis (or diameter) of an ellipse or hyperbola: that which is conjugate to the transverse axis, the minor axis. Conjugate hyperbolas: hyperbolas that have the same axes and asymptotes, but the principal axis of each is the second axis of the other. Conjugate lines: two lines the pole of each of which, with respect to a conic, lies on the other. Conjugate point (of a curve): an isolated point whose coordinates satisfy the equation of the curve, an acnode (so also conjugate oval). Conjugate planes: see quot. 1862. Conjugate points: points the polar of each of which, with respect to a conic, passes through the other.
1680. Sir J. Moore, Doctrine of Sphere, 67. This shall be the Conjugate Semidiameter of the Ellipsis.
1726. trans. Gregory’s Astron., I. 438. To find the conjugate Diameters of an Ellipse which passes thro’ five given Points.
1806. Hutton, Course Math., II. 112. All the Parallelograms inscribed between the four Conjugate Hyperbolas are equal to one another.
1862. Salmon, Geom. 3 Dim. (1874), § 71. Three diametral planes are said to be conjugate when each is conjugate to the intersection of the other two, and three diameters are said to be conjugate when each is conjugate to the plane of the other two.
1876. Leishman, Midwifery, ii. (ed. 2), 34. The conjugate diameter [of the pelvis] is … increased from above downwards.
1880. Taylor, Geom. Conics, 76. The conjugate axis of any central conic is occasionally called its minor axis.
1885. Leudesdorf, Cremona’s Proj. Geom., 47. Let A, B, C be the given points (lying on a straight line) and let A and B be conjugate to each other.
b. Optics.
Conjugate foci (of a mirror or lens): two points so situated that if a luminous point be placed at either, its rays are reflected or refracted to the other; so conjugate focal distance. Conjugate mirrors: two parabolic mirrors so placed face to face that rays of heat or light emanating from the focus of either are reflected in parallel lines to the second and thence to its focus.
1831. Brewster, Optics, i. 11. The points A and F have been called conjugate foci, because if either of them be the radiant point the other will be the focal point. Ibid. (1831), Nat. Magic, iv. (1833), 85. The two conjugate focal distances of the lens.
1881. Tyndall, in Nature, XXIII. 375. The silvered mirrors … acting sometimes singly, and sometimes as conjugate mirrors.
c. Electr. as in Conjugate branch (of a divided circuit), current, etc.: see quots. (Formerly used in a more general sense.)
1782. Phil. Trans., LXXII. App. p. xxi. (transl. Volta). When an insulated conductor is opposed or presented to another conductor whatever, I call it a conjugate conductor.
1881. J. C. Maxwell, Electr. & Magn., I. 367. If there be more possible electrodes than two, the conductor may have more than one independent current through it, and these may not be conjugate to each other.
1882. Everett, Deschanel’s Nat. Philos., § 758. When this condition is fulfilled, the remaining pair of opposite branches are conjugate, that is to say, a battery in one produces no current in the other. Ibid., § 759. When there is equality between the two products of opposite resistances … the current in either of the two remaining branches will be independent of the electro-motive force of the battery in the other; and these two branches are still said to be conjugate.
B. sb.
1. One of a group of words directly derived from the same root or stem, and usually of kindred meaning.
a. 1586. Answ. to Cartwright, 45. These be coniugates, an vnlawfull minister, and his vnlawfull ministerie.
1588. Fraunce, Lawiers Log., I. xii. 50 b. Conjugates … as justice, just, justly.
1655. Bramhall, in Hobbes, Liberty, Necess. & Chance (1841), 83. We have learned in the rudiments of logic, that conjugates are sometimes in name only, and not in deed.
1836. Whewell, Pref. Mackintosh’s Eth. Philos., 18. The word utility, and its conjugates, do not express our judgments in cases of moral conduct.
1862. Marsh, Eng. Lang., xxvi. 421. Few languages are richer than English in approximate synonyms and conjugates.
† 2. Anything connected or related in idea with another. Obs.
1605. Bacon, Adv. Learn., II. xiv. § 9. The cogitations of man do feign unto them relatives, parallels, and conjugates, whereas no such thing is.
1663. J. Spencer, Prodigies (1665), 46. A mighty imagination, which delights in easie conjugates, parallels, and symbolizing instances.
3. Chem. Short for conjugate compound, acid, or radical: see A. 3.
4. Math. Short for conjugate axis, diameter, point, etc.: see A. 6 a.
1726. trans. Gregory’s Astron., I. 79. Draw a tangent PZ, and a Diameter PM, and a Conjugate to it ICK parallel to PZ.
1807. Hutton, Course Math., II. The Conjugate to any diameter, is the line drawn through the centre, and parallel to the tangent of the curve at the vertex of the diameter.
1823. P. Nicholson, Pract. Build., 302. A semi-ellipse, described on a conjugate equal to the width of the pier.
1885. Leudesdorf, Cremona’s Proj. Geom., 101. In an involution … the elements are conjugate to one another in pairs; i.e. each element has its conjugate.
