n. 1 a junction, joint, or seam. 2 Anat. a the joint between two bones. b a band of nerve tissue connecting the hemispheres of the brain, the two sides of the spinal cord, etc. c the line where the upper and lower lips, or eyelids, meet. 3 Bot. any of several joints etc. between different parts of a plant. commissural adj.
[ ME f. L commissura junction (as COMMIT) ]