a. Forms: 6 eccentrike, 6–9 excentric(k(e, 7–8 eccentrick, 7 ec-, excentrique, 7– eccentric. [ad. late L. eccentricus, f. Gr. ἔκκεντρος eccentric as opposed to concentric (f. ἐκ out of + κέντρον center); see -IC; the word is found in all the Romanic langs.: Fr. excentrique (14th c. in Littré), Pr. excentric, It. eccentrico, Sp. excéntrico.] A. adj.
1. Of a circle: Not concentric with another circle (const. to). Of two or more circles: Not mutually concentric. Chiefly used of circles of which one is within the other. † Eccentric orb: in the Ptolemaic astronomy, an orbit not having the earth precisely in its center (afterwards sometimes used in a Copernican sense: an orbit not having the sun precisely in its center).
1551. Recorde, Cast. Knowl. (1556), 247. These two circles … are eccentrike, for that they haue not one common centre.
1621. Burton, Anat. Mel., II. ii. III. (1651), 251. Which howsoever Ptolemy, [etc.], maintain to be reall orbes, excentrick, concentricke.
1656. trans. Hobbes’ Elem. Philos. (1839), 431. This annual orb [of the earth] is eccentric to the sun.
† b. fig. Not agreeing, having little in common. Const. from, to. Obs.
1607–12. Bacon, Wisdom, Ess. (Arb.), 184. His owne endes, which must needes be often eccentrique to the endes of his Master or State.
1666. Collins, in Rigaud, Corr. Sci. Men (1841), II. 463. My book of Accounts … is so eccentric to your studies as I thought it unworthy your acceptance.
1670. Sanderson, in Ussher, Power Princes (1683), Pref. A task … altogether excentrick from their function and calling.
2. That has its axis, its point of support, etc., otherwise than centrally placed. Cf. B. 2.
1647. Ward, Simp. Cobler (ed. 3), 46. Else the world will be Excentrick, and then it will whirle.
1743. Savery, in Phil. Trans., XLVIII. 176–7. Large object-glasses for telescopes are not commonly well center’d…. I … return’d them [two faulty ones], and had two sent me again, as eccentric well nigh as the former ones.
1825. N. Wood, Rail-roads, 148. This eccentric circle is loose upon the axle…; a circular hoop … fits the circumference of the eccentric motion.
1831. J. Holland, Manuf. Metals, I. 92. That ingenious but simple contrivance the eccentric wheel.
3. Not centrally placed. Of an axis, etc.: Not passing through the center.
1849. Sir J. Herschel, Outlines Astron., iii. § 141 (1858), 83. If the axis be excentric.
1882. Vines, Sachs’ Bot., 203. The organic centre of the transverse section does not usually coincide with the geometrical centre, as is easily seen in the transverse sections of most petioles and horizontal branches with an ‘eccentric’ pith.
1884. Bower & Scott, De Bary’s Phaner. & Ferns, 365. The position of the bundle in the root is from the first slightly eccentric.
† b. Of a locality: Remote from the center; out of the way. [So Fr. quartier excentrique.] Obs.
1800. T. Jefferson, Writ. (1859), IV. 312. [The College] is … eccentric in its position, exposed to all bilious diseases abandoned by the public care.
c. Phys. (See quot.)
1876. Bernstein, Five Senses, 20. The sensation of sight can only take place … in the brain … and yet we transfer the object seen to the external world surrounding us. This fact is called the law of eccentric sensation.
† 4. Misused for: Having no center. Obs.
1633. T. Adams, Exp. 2 Peter iii. 7. 1228. Onely that is Eccentrique, which was never made.
1652. Benlowes, Theoph., II. xli. 28. Deaths Hell Deaths Self out-deaths! Vindictive Place!… Excentrick Space!
1681. trans. Willis’ Rem. Med. Wks., Voc., Eccentric, Without Centre.
5. Of orbital motion: Not referable to a fixed center of revolution; not circular. Of a curve, an elliptic, parabolic or hyperbolic orbit: Deviating (in greater or less degree) from a circular form.
1642. Howell, For. Trav., 77. Let these Lights … be kept from irregular and eccentrique motions.
1692. Bentley, Boyle Lect., vii. 247. They could not possibly acquire such Revolutions … in Ellipses very little Eccentric.
1796. Morse, Amer. Geog., I. 32. Like other planets moving about the sun in very eccentric ellipses.
1866. Sir J. Herschel, Fam. Lect. Sc., Comets, 104. A comet moves round the sun … in an immensely elongated, or as it is termed a very eccentric, ellipse.
b. transf. Of a heavenly body: Moving in an orbit deviating (more or less) from a circle.
a. 1721. Keill, trans. Maupertuis’ Diss. (1734), 63. The Comets are no more … than very excentric Planets.
a. 1791. Wesley, Serm., lxix. 8, Wks. 1811, IX. 249. Those horrid, eccentric orbs.
1816. J. Smith, Panorama Sci. & Art, I. 581. When very eccentric planets or comets go round any flat star, in orbits much inclined to its equator.
c. Eccentric anomaly: the true anomaly of a planet moving in an eccentric orbit (opposed to the mean anomaly). Eccentric equation: see EQUATION.
6. fig. Regulated by no central control.
a. Of actions, movements, and things in general: Irregular, anomalous, proceeding by no known method, capricious.
c. 1630. Drumm. of Hawth., Poems, 195. Finding all eccentrick in our times.
1792. Burke, Pres. State Affairs, Wks. I. 586. The eccentrick aberration of Charles the Second.
1848. Macaulay, Hist. Eng., I. 657. This eccentric clemency has perplexed some writers, and has drawn forth ludicrous eulogies from others.
b. Of persons and personal attributes: Deviating from usual methods, odd, whimsical.
1685–6. Loyal Poems, Shaftesbury’s Farew., 6. The brightest, yet the most excentrick Soul.
1695. Ld. Preston, Boeth., II. 68. The Extravagance of Excentrick and irregular Desires.
1771. Mackenzie, Man Feel., xxxiv. (1803), 61. His motives were rather excentric.
1802. Mar. Edgeworth, Moral T. (1816), I. Pref. 7. [Forester is the picture of] an eccentric character.
1836. H. Rogers, J. Howe, ii. (1863), 19. That great, though unequal and eccentric genius.
7. a. quasi-adv. b. absol. quasi-sb.
1672. Dryden, Conq. Granada, I. V. i. He moves excentrique, like a wand’ring Star.
1870. Lowell, Among my Bks., Ser. I. (1873), 203. Wordsworth never quite saw the distinction between the eccentric and the original.
B. sb.
† 1. [= eccentric circle, orb; see A. 1.] In Ptolemaic astronomy: A circle or orbit not having the earth precisely in its center. Obs. exc. Hist.
[1398. Trevisa, Barth. De P. R., VIII. xi. (1495), 317. The fyrste meuynge of a planete … is a cercle that hyghte Ecentricus.]
1561. Eden, Arte Nauig., I. xx. 22. Eccentricke, is a circle which hath his center distant … from the center of the worlde.
1646. Sir T. Browne, Pseud. Ep., VI. v. 293. The Perigeum or lowest part of the eccentric.
1724. Watts, Logic (1736), 225. Excentricks and Epicycles of Ptolomy.
1783. W. F. Martyn, Geog. Mag., I. Introd. 14. A number of circles called eccentrics and epicycles.
fig. a. 1660. Hammond, Wks., IV. 551. Reserving … somewhat for common calamities, somewhat as it were for the universal motion of the whole body, somewhat for eccentricks.
2. Mech. A circular disc fixed on a revolving shaft, some distance out of center, working freely in a ring (the eccentric strap), which is attached to a rod called an eccentric rod, by means of which the rotating motion of the shaft is converted into a backward-and-forward motion. Its most frequent use is for working the slide-valve of a steam-engine. (Earlier eccentric circle, motion; see A. 2).
1827. Specif. Mandelay’s Patent No. 5531. It consists … in the application of an eccentric to work the slide [valve].
1838. Public Wks. Gt. Brit., 69. The slides are worked by four fast eccentrics … instead of two loose ones.
1881. Mechanic, § 657. 302. The set screw in the eccentric shall be downwards.
3. [Cf. A. 6 b.] A person whose conduct is irregular, odd or whimsical.
1832. Scott, St. Ronan’s, Introd. Men of every country playing the eccentric.
1850. Kingsley, Alt. Locke, vi. (1879), 65. I have given no description of the old eccentric’s abode.
C. Attrib. and Comb. a. In various parts connected with the eccentric that works the slide-valve in a steam-engine, as eccentric-catch, -hook, -rod. Also eccentric-hoop, -ring, or -strap, the ring in which the eccentric revolves.
b. In various machines or parts of machines, whose distinctive feature is that they are worked by an eccentric wheel or depend upon an eccentric arrangement; as eccentric-arbor, -chuck, -cutter (in Turning), -engraving, -fan, -gear, -pump.
1859. Handbk. Turning, 57. Eccentric turning … includes all the various … work for which the powers of a lathe are … celebrated. Ibid., 87. Eccentric chuck.
1884. F. J. Britten, Watch & Clockm., 100. When the three screws are loosened the two parts of the eccentric arbor may be shifted.
