What is the term for a body of air with generally the same temperature and moisture content?

The term for a body of air with generally the same temperature and moisture content is "an air mass." An air mass signifies a large volume of air that exhibits uniform characteristics in terms of temperature and humidity throughout its extent. These characteristics are typically acquired from the surface over which the air mass forms. For instance, an air mass that forms over a warm ocean will be warm and moist, while one that forms over a cold land area will be cool and dry.

This understanding is crucial in meteorology as different air masses can influence weather patterns. Observations and analysis of air masses help meteorologists predict weather changes and understand atmospheric conditions more clearly.

In contrast, a front refers to the boundary between two different air masses, a system denotes a larger weather pattern or phenomenon, and a zone is a less specific term that could refer to any area with particular characteristics, but does not specifically denote uniformity in temperature and moisture content like an air mass does.