key blockn.
/ˈkiː blɒk/, U.S. /ˈki ˌblɑk/ 1. A block placed at the summit of an arch or other structure, locking the whole together; a keystone.
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society > leisure > the arts > visual arts > architecture > arch > [noun] > parts of > keystone
key1608
keystonea1637
key-piece1669
sagitta1703
key block1823
1823 London Lit. Gaz. 25 Oct. 674/2 The huts themselves are entirely made of square blocks of solid snow, with a larger key-block at the top of the rotunda.
1894 N. S. Shaler et al. U.S.A. iv. 234 The last, or key block, is perfectly horizontal and firmly wedges in and binds the whole structure [sc. an igloo].
1915 B. A. Etcheverry Irrigation Pract. & Engin. II. viii. 182 Supporting frames..extending up to the center of the arch, where they are connected together by a wedge-shaped key block.
1933 Financial Times 28 Dec. 8/2 Stone has been sparingly used for cornice key blocks and capping.
2001 Derby Evening Tel. (Nexis) 1 Nov. 40 The side gates consisted of rusticated stone aedicules, with an arch centred by keyblocks embellished with further vermiculation.
2. Printing and Printmaking. = keystone n.1 4.
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society > communication > printing > types, blocks, or plates > blocks, plates, or transfers > [noun] > blocks
factotum1676
fac1841
key block1867
type-block1875
society > leisure > the arts > visual arts > printmaking > [noun] > guide for colour registration
key plate1856
key block1867
key drawing1868
1867 Amer. Lit. Gaz. & Publishers' Circular 1 Mar. 271/2 Sometimes this plan was reversed—the colors being printed first, and the key-block last.
1894 Studio 3 128/1 We are permitted to reproduce the key blocks of two of them [sc. prints].
1937 Discovery Mar. 77/1 In order to get the colours fitting accurately, prints are taken from the first or key-block and pasted on to each successive block.
1966 W. T. Berry & H. E. Poole Ann. Printing 241/1 They vary in quality, many being spoiled by the heavy impression from the wood key block.
2004 I. Chilvers Oxf. Dict. Art (ed. 3) 147/1 It is usual to make a key block with the design in outline, and to cut this first so that the main lines can be transferred to other blocks.
3. In quarrying: the first block or blocks to be removed from a new layer of stone.
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society > occupation and work > materials > raw material > stone or rock > [noun] > material taken from quarry
quarrela1400
rockstone?1545
pit stone1659
stock1709
banker1853
key block1881
society > occupation and work > materials > raw material > stone or rock > [noun] > material taken from quarry > first block to be removed
key block1881
1881 Libr. Universal Knowl. IX. 478 One of the blocks, called the key block, is then broken off at the base by wedging and lifted out with a crane.
1884 Manufacturer & Builder Oct. 230/2 The modern system would be to cut out the key-block with the channeling machine, as a plug is taken from a watermelon.
1934 O. Bowles Stone Industries ii. ix. 212 In opening up a new floor the first blocks to be removed are known as ‘key blocks’.
1967 Amer. Speech 42 290 Once this first troublesome block, called the key block, is out, further quarrying becomes much easier.
2002 H. L. Hartman & J. M. Mutmansky Introd. Mining Engin. (ed. 2) vii. 193 The cut is established by cutting or channeling a key block.
This entry has been updated (OED Third Edition, December 2012; most recently modified version published online March 2022).
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n.1823