What is the dewpoint in meteorological terms?

The dewpoint in meteorological terms is defined as the temperature at which a parcel of air becomes saturated with moisture, meaning it can no longer hold additional water vapor. At this temperature, the air is fully saturated, and any further cooling or addition of moisture will result in condensation, leading to the formation of dew, fog, or clouds. This point is critical in understanding humidity and the potential for precipitation, as it directly relates to the moisture content of the air.

In contrast to the other options, the dewpoint is not about the maximum water-holding capacity of air (which is variable and depends on the temperature), nor is it simply a measure of temperature or rainfall onset. The dewpoint specifically indicates the saturation point, making it fundamental for meteorological studies and weather predictions.