Pl. fulcra. Also 7 fulchrum. [a. L. fulcrum (in class.L. ‘the post or foot of a couch’), f. root of fulc-īre to support, prop.]
1. A prop or support; now only spec. in Mech. the point against which a lever is placed to get purchase or upon which it turns or is supported.
1674. Petty, Disc. Dupl. Proportion, 41. Square Rods or Pieces made of any Clean Timber, or other Materials, whose Ends let be supported with convenient Blocks or Fulcra.
1690. Boyle, Med. Hydrostat., ix. 60. The Ballance hangs on a stable Fulcrum.
1774. Goldsm., Nat. Hist. (1776), VII. 182. They [serpents] entirely want a fulcrum, if I may so express it, from whence to take their spring.
1802. Paley, Nat. Theol., viii. § 2. The same spine was also … to afford a fulcrum, stay, or basis … for the insertion of the muscles which are spread over the trunk of the body.
1803. J. Wood, Princ. Mech. (ed. 6), iv. 50. The Lever is an inflexible rod, moveable, in one plane, upon a point which is called the fulcrum, or center of motion.
1832. De la Beche, A Geological Manual (ed. 2), 40. If the centre of gravity of the mass chances to be high and far removed from the perpendicular of its fulcrum, the stone falls from its elevation, and becomes constantly rounder by the continuance of decomposition, till it assumes one of the spheroidal figures which the granite boulders so often exhibit.
1855. Holden, Hum. Osteol. (1878), 141. The use of the scapula is to afford a movable fulcrum for the motions of the arm.
1869. Gillmore, Reptiles & Birds, ii. 59. They hook themselves on to a tree, which gives them the power of a double fulcrum.
b. fig.
1678. Cudworth, Intell. Syst., 472. The most excellent Fulcrum of the Soul, the perswasion of the Everliving God.
a. 1679. T. Goodwin, Wks. (1682), II. IV. 335. Our Hearts will need a most special strong fulchrum, support and susteiner (as the word imports).
1804. W. Taylor, in Ann. Rev., II. 334/2. If they chose to go to war, this was the most important interest of the nation involved in the discussion, and should have been selected as the fulcrum of indignation.
1850. Merivale, Rom. Emp. (1865), I. iv. 172. The consulship was the fulcrum from which the whole Roman world was to be moved.
1853. Sir H. Douglas, Milit. Bridges (ed. 3), 222. A footing once gained is a fulcrum which should never be lost, and never is so but by misconduct.
2. (Chiefly pl.) a. Bot. Accessory organs or appendages of a plant; e.g., bracts, stipules, tendrils, etc.
1785. Martyn, Rousseau’s Bot., xxxi. 484. The parts I now allude to, are what he [Linnæus] calls Fulcra, props or supports of the plant.
1807. J. E. Smith, Phys. Bot., xvii. 218, chapter title. Of the Several Kinds of Fulcra, or Appendages to a Plant.
1874. M. Cooke, Fungi (1875), iii. 62. In an exotic genus, Meliola, the fulcra, or appendages, as well as the mycelium, are black.
b. Ichth. (pl.) The small osseous scales arranged in a row and situated on the anterior ray of the fins of many ganoid fishes.
1880. Günther, Fishes, 360. Vertical fins with a single series of fulcra in front.
1885. trans. Claus’ Zoöl., II. 164. The spine-like splints known as fulcra.
