1. A wind system that influences large climatic regions and reverses direction seasonally.
2. A wind from the southwest or south that brings heavy rainfall to southern Asia in the summer.
3. A similar seasonal wind, as in the southwest United States, that brings increased rainfall.
4. The rain that comes with any of these winds or wind systems.
[Obsolete Dutch monssoen, from Portuguese monção, from Arabic mawsim, season, from wasama, to mark; see wsm in Semitic roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 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.