(1):
(n.) A collection of fibers connecting parts of the brain or spinal marrow; a chiasma.
(2):
(n.) The point of union between two parts, as the angles of the lips or eyelids, the mandibles of a bird, etc.
(3):
(n.) A joint, seam, or closure; the place where two bodies, or parts of a body, meet and unite; an interstice, cleft, or juncture.
(4):
(n.) The line of junction or cohering face of two carpels, as in the parsnip, caraway, etc.