monsoon

Short definition from Wiktionary

Noun

1. 1
   Any of a number of winds associated with regions where most rain falls during a particular season.
2. 2
   Tropical rainy season when the rain lasts for several months with few interruptions.
3. 3
   The rains themselves.
4. 4
   Entire meteorological systems with such characteristics.
5. 5
   Any heavy rainstorm.