‖ exostosis
(ɛksɒˈstəʊsɪs)
[mod.L., a. Gr. ἐξόστωσις (Galen) outgrowth of bone, f. ἐξ (see ex- prefix2) + ὀστέον bone.]
1. Path. a. The formation of bone on another bone, or on some other structure in the body. b. concr. A bony tumour found upon a bone or cartilage.
| a. 1804 Abernethy Surg. Observ. 32 Tumours growing near, and compressing the surface of bones, frequently occasion a degree of exostosis. |
| b. 1736 Freke in Phil. Trans. XLI. 369 It may be said to come under the Denomination of an Exostosis. 1782 W. Heberden Comm. Hist. & Cure Dis. xi, Except some exostoses of the vertebræ of the thorax. 1839 Todd Cycl. Anat. II. 220/2 Exostosis appears most frequently on the upper jaw. 1868 Darwin Anim. & Pl. II. xii. 23 Bony exostoses on the legs [of a horse] caused by too much travelling on hard roads. |
2. Bot. ‘A diseased condition in plants, in which hard masses of wood are produced, projecting like warts or tumours from the main stem or roots’ (Treas. Bot. 1866).