1. The edge of a knife; also transf., anything keenly cutting. Also attrib. = knife-edged.
1876. Geo. Eliot, Dan. Der., xxiii. Her pride had felt a terrible knife-edge.
1877. E. R. Conder, Bas. Faith, ii. 80. To insert the knife-edge of a sharp discrimination.
1884. Tennyson, Becket, II. i. 149. I would creep, crawl over knife-edge flint Barefoot.
2. A wedge of hard steel, on which a pendulum, scale-beam, or the like, is made to oscillate.
1818. Capt. Kater, in Phil. Trans., CVIII. 35. For the construction of the pendulum, it became of considerable importance to select a mode of suspension equally free from objection. Diamond points, spheres, and the knife edge, were each considered.
1851. Illustr. Catal. Gt. Exhib., 1266. The pendulum … is suspended on a knife-edge of very hard bronze.
1854. J. Scoffern, in Orr’s Circ. Sc., Chem., 4. Delicate balances have their points of oscillation composed of a steel knife-edge working on agate planes.
b. transf. and fig.
1871. L. Stephen, Playgr. Europe, v. (1894), 120. Balancing ourselves on a knife-edge of ice between two crevasses.
1897. Stevenson, in Pall Mall Mag., Aug., 524. She had come to the party, in consequence, on the knife-edge of anticipation and alarm.
Hence Knife-edged a., having a thin sharp edge like a knife.
1863–76. Curling, Dis. Rectum (ed. 4), 46. A pair of knife-edged scissors.
1865. Geikie, Scen. & Geol. Scot., vi. 118. A mere knife-edged crest, shelving steeply into the glens on either side.
1883. J. D. Jerrold Kelly, in Harper’s Mag., Aug., 445/2. A knife-edged craft with wide keel.
