What best defines rainfall?

Rainfall is best defined as a form of precipitation, which encompasses all processes where water vapor condenses in the atmosphere and falls back to the earth in various forms. This includes not just rain, but also snow, sleet, hail, and drizzle. While the term "rainfall" often brings to mind liquid precipitation specifically, the broader definition captured in the choice that includes all forms of precipitation accurately reflects meteorological terminology.

Identifying rainfall solely as water that evaporates from the earth does not capture the complete cycle of water, as evaporation is just one part of the water cycle that also includes condensation and precipitation. Describing rainfall as only liquid precipitation limits the definition and overlooks the other forms of precipitation that can occur. Defining it as a type of groundwater misconstrues the term, as groundwater refers to water stored beneath the earth's surface, while rainfall originates from clouds and occurs in the atmosphere. Thus, the most comprehensive and accurate definition of rainfall encompasses all its various forms of precipitation.