[ad. L. convexus vaulted, arched, rounded, app. an old pa. pple. (= convectus) of convehĕre to carry or bring together (because in forming an arch the extremities of the surface are brought together): in Lat. convexus was sometimes used to include concavus: see B. 1 c. By Milton stressed conve·x, which is not infrequent with later poets.] For a possible early use see CONVERS.
A. adj.
1. Curved like the outside of a circle or sphere; having a curvature that bulges toward the point of observation; the reverse of concave.
1571. Digges, Pantom., Pref. A ij. Manyfolde superficies, playne Conuex and Concaue.
1594. Blundevil, Exerc., III. I. (ed. 7), 271. The upper part of such a Vault is sayd to be Convex and the inward part Concave.
1614. Bp. Hall, Recoll. Treat., 695. The convexe or out-bowed side of a vessell.
1706. Lond. Gaz., No. 4292/3. Letters-Patents for the Convex-Lamps.
1794. Sullivan, View Nat., I. 459. Flint breaks with smooth surfaces, one of which is convex, the other concave.
1853. Herschel, Pop. Lect. Sc., v. § 13 (1873), 191. The earth’s surface is … less convex—that is, flatter—as we approach its poles on all sides from the equator.
1879. A. R. Wallace, Austral., ix. 195. Its coast being concave instead of convex, and, therefore less open to the cool sea.
b. esp. of glasses, lenses, mirrors, etc., of this shape used for optical purposes.
1571, 1662. [see CONCAVE a. 2 b].
1751. Chambers, Cycl., s.v., A convex mirrour represents its images smaller than the objects.
1822. Imison, Sc. & Art, I. 237. When parallel rays … fall upon a double convex lens, they will be refracted.
1833. N. Arnott, Physics (ed. 5), II. I. 130. The light is made by a convex glass or lens to converge to one point or focus.
1869. Tyndall, Notes on Light, § 104. 16. All the foci, and all the images of a convex mirror are virtual.
2. Comb., as convex-concave.
1840. Carlyle, Heroes (1858), 263. No twisted, poor convex-concave mirror, reflecting all objects with its own convexities and concavities.
B. sb. [elliptical use of the adj.]
† 1. A convex surface or body; a vault, arch, hemisphere, etc., as viewed from without. Obs.
1626. Bacon, Sylva, 222. Flat against Flat, and Convex against Convex.
1659. T. Pecke, Parnassi Puerp., 160. The sublime convex of the Quirine Hils.
1727. De Foe, Hist. Appar. (1840), 56. He has apparently posted an army of ministering Spirits … round this convex, this globe the earth.
1796. Morse, Amer. Geog., I. 56. A spherical convex nearly as round as the globe itself.
b. The convex part of anything.
1703. Moxon, Mech. Exerc., 203. The middle of the Convex of the Hook.
1816. Keatinge, Trav., II. 262. Placed on the convex of a piece of timber.
c. By the poets often applied to the vault of the sky or heavens, hell, etc. Cf. L. convexum, -a.
1627. May, Lucan, IX. (1631), 1. And takes Up to the convexe of the sky his flight.
1667. Milton, P. L., II. 434. This huge convex of Fire … immures us round Ninefold. Ibid., VII. 266. In circuit to the uttermost convex Of this great Round.
1700. Prior, Carmen Seculare, 514. Through the large Convex of the Azure Sky.
a. 1740. Tickell, Royal Progress, 123, in Poet. Wks. (1796?), 29.
| From east to west burns thro’ th’ ethereal frame, | |
| And half heav’n’s convex glitters with the flame. |
2. A convex glass or lens.
1705. Berkeley, Common-pl. Bk., Wks. IV. 480. Qu. if blind would think things diminish’d by convexes.
1708. J. Phillips, Cyder, I. p. 22.
| She found the polish’d Glass, whose small Convex | |
| Enlarges to ten Millions of Degrees | |
| The Mite, invisible else, of Nature’s Hand | |
| Least Animal. |
3. A card prepared for cheating by being cut slightly convex along two edges.
1873. [see CONCAVE sb. 4].
