symphysis

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A growing together of bones originally separate, as of the two pubic bones or the two halves of the lower jawbone.
• noun A line or junction thus formed.
• noun An articulation in which bones are united by cartilage without a synovial membrane.
• noun The coalescence of similar parts or organs.

from The Century Dictionary.

• noun In anatomy and zoology: The union or connection of bones in the middle line of the body, either by confluence, by direct apposition, or by the intervention of cartilage or ligament; also, the part, or configuration of parts, resulting from such union or connection.
• noun Some point or line of union between two parts; a commissure; a chiasm: as, the symphysis of the optic nerves.
• noun Attachment of one part to another; a growing together; insertion or gomphosis with union: as, the symphysis of teeth with the jaw. See acrodont, pleurodont.
• noun Coalescence or growing together of parts so as to close a natural passage; atresia.
• noun In botany, a coalescence or growing together of similar parts.

from the GNU version of the Collaborative International Dictionary of English.

• noun An articulation formed by intervening cartilage.
• noun The union or coalescence of bones; also, the place of union or coalescence. Cf. articulation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The process of two, originally separate bones growing together as the mammalian subject matures, as with the pubic bones or lower jawbones in humans.
• noun A line discernable on X-ray showing such fusion.
• noun The cartilaginous material that adjoins and facilitates the junction of such bones, with or without synovia.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a growing together of parts or structures
• noun an abnormal adhesion of two or more structures