n.1 a wind in S. Asia, esp. in the Indian Ocean, blowing from the south west in summer (wet monsoon) and the north east in winter (dry monsoon).
2 a rainy season accompanying a wet monsoon.
3 any other wind with periodic alternations.
Derivatives:
monsoonal adj.
Etymology: obs. Du. monssoen f. Port. mon{ccedil}|.o f. Arab. mawsim fixed season f. wasama to mark