The American Heritage® Dictionary of the English Language, 4th Edition
n. A crossing in the shape of an X.
n. Anatomy An X-shaped crossing, especially of nerves or bands of nerve fibers, connecting corresponding parts on opposite sides of the brain or spinal cord.
n. A crossing or intersection of lines etc. so as to form an X-shape.
the GNU version of the Collaborative International Dictionary of English
n. Act of crossing at an acute angle, or state of being thus crossed; an intersection in the form of an X
The Century Dictionary and Cyclopedia
n. The act of crossing or intersecting; an intersection; the crossing of two lines, rays, fibers of nerves, etc.
n. The state of being decussated, or that which decussates; a chiasm.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. an intersection or crossing of two tracts in the form of the letter X
Word Usage
"Prof. Hamilton, of Aberdeen, claims that the corpus callosum is not a commissure, but the decussation of cortical fibers on their way down to enter the internal and external capsules of the opposite side."