What term describes air mass that forms over large bodies of water?

The term that describes an air mass formed over large bodies of water is "maritime." Maritime air masses typically have higher humidity levels because they collect moisture from the ocean surface. This characteristic influences weather patterns significantly, often leading to cloud formation and precipitation when these air masses move over land.

Maritime air masses are distinct from continental air masses, which form over land and generally have lower humidity. While equatorial and polar are classifications based on the latitude and temperature characteristics of air masses, they do not directly indicate the source of moisture, which is the defining feature of maritime air masses. Thus, "maritime" is the correct term for air masses originating over oceans or large lakes and is crucial in understanding how moisture and temperature influence local climates.