[mod.L., a. Gr. σύμφυσις a growing together, esp. of the bones, f. σύν SYM- + φύσις growth.]
1. Anat. and Zool. The union of two bones or skeletal elements originally separate, either by fusion of the bony substance (synostosis) or by intervening cartilage (synchondrosis); the part, or line of junction, where this takes or has taken place: used esp. of such union of two similar bones on opposite sides of the body in the median line, as that of the pubic bones (symphysis pubis) or of the two halves of the lower jaw-bone (s. mandibulæ or menti).
1578. Banister, Hist. Man, I. 4. That kynde of coniunction of bones, that is called Symphysis: as when they are so vnited together that they haue motion neither manifest, nor obscure.
1634. T. Johnson, Parey’s Chirurg., VI. xlii. (1678), 165. The bones are composed after two sorts, that is, by Arthrosis … and by Symphysis.
1779. Monthly Rev., LX. 61. The room gained by slitting the Symphysis of the Pubis will not, in many cases, allow the child’s head to pass.
1800. Phil. Trans., XC. 433. The two portions of the lower jaw, instead of terminating at the symphisis [sic], where they join, become two thin plates, and are continued forwards.
a. 1856. H. Miller, Footpr. Creat., Notes Suite Fossils (1861), 317. The fourth tooth of the under jaw, reckoning from the symphysis.
1879. Gillmore, trans. Figuier’s Reptiles & Birds, ii. 44. The two halves of the lower jaw in Ophidians … are not united by a bony symphysis, but by an elastic ligament.
1870. Rolleston, Anim. Life, Introd. 51. Except in Rhea, the ischia [in birds] never form any symphysis; nor do the pubic bones, except in Struthio Camelus.
b. Occasionally applied to a union or fusion, or a point or line of junction, of other parts either originally or normally separate.
1891. Cent. Dict., s.v., The symphysis of the optic nerves,… the symphysis of teeth with the jaw.
1913. Dorland, Med. Dict., s.v., Cardiac s[ymphysis], adhesion of the parietal and visceral layers of the pericardium.
† c. Surg. (See quots.) Obs.
1767. Gooch, Treat. Wounds, I. 160. We see what wounds are curable by Symphysis, and what by Syssarcosis.
1828–32. Webster, Symphysis.… In surgery, a coalescence of a natural passage; also, the first intention of cure in n wound.
2. Bot. Coalescence or fusion of parts of a plant normally distinct.
1866. Treas. Bot., Symphysis, a growing together.
