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.]
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