dec·us·sa·tion (dĕk′ə-sāshən, dē′kə-)
1. A crossing in the shape of an X.
2. 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.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.