"monsoon" is a word which means "seasonal wind".
Here in the southwest USA, the normal pattern for winter winds is from the north, and for summer is from the south. The monsoon is defined as when the wind comes up from the south bringing moist (relatively) air from the gulf of california or the gulf of mexico. In the spring and fall when the weather pattern changes, it usually changes suddenly and the overall temperature changes (for the season) by 20 degrees in a few days.
On the weather reports in the SW, the talk of monsoon becomes almost constant at this time of year. The thunderstorms we can get are "biblical".