humidity

n. dampness, moistness, mugginess

Humidity is the amount of water vapor in a sample of air compared to the maximum amount of water vapor the air can hold at any specific temperature. Absolute humidity, relative humidity and specific humidity are different ways to express the water content in a parcel of air. Relative humidity is the most frequently used of these expressions because of its importance in weather forecasting. Relative humidity indicates the likelihood of precipitation, dew, or fog. High relative humidity makes people feel hotter outside in the summer because it reduces the effectiveness of sweating to cool the body by preventing the evaporation of perspiration from the skin. This effect is calculated in a heat index table. Warm water vapor has more thermal energy than cool water vapor and therefore more of it evaporates into warm air than into cold air.
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Hu·mid·i·ty n. Dampness, especially of the air. humidity, n pertaining to the level of moisture in the atmosphere, the amount varying with the [more]Humidity - Community and Resources

Noun
1. wetness in the atmosphere
(synonym) humidness
(hypernym) wetness
(hyponym) mugginess
(derivation) humidify, moisturize, moisturise

(n.)
Moisture; dampness; a moderate degree of wetness, which is perceptible to the eye or touch; -- used especially of the atmosphere, or of anything which has absorbed moisture from the atmosphere, as clothing.