Definition of "decussate" []

• To cross or become crossed so as to form an X; intersect. (verb-transitive)
• Intersected or crossed in the form of an X. (adjective)
• Botany Arranged on a stem in opposite pairs at right angles to those above or below, resulting in four vertical rows: decussate leaves. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The leaves on this plant are arranged in pairs opposite one another, with successive pairs at right angles to each other ( "decussate") along the red stem."
• "There are certain other nervous cords which decussate, are attached (to the vertebrae?), and are extended from both sides of them."
• "The optic nerves give off no branches in passing from their origin in two ganglia situated between the cerebrum and the cerebellum, and their termination in the eyeballs; but, in the middle of their course, they _decussate_, or unite in one mass."