the amount of rain that falls on a single occasion
"The heavy storm resulted in an unprecedented rainfall of three inches within just two hours."
In plain English: Rainfall is simply rain that falls from clouds and hits the ground.
"The heavy rainfall caused several streets to flood during the storm."
Usage: Use rainfall to refer specifically to the total quantity or depth of precipitation during one event, rather than using it as a synonym for general weather conditions. This term is essential when discussing meteorological data where measuring specific amounts matters more than describing whether it rained at all.
The word rainfall is a straightforward combination of the words rain and fall. It was formed to describe precipitation that drops from clouds to the ground.