humidity

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Dampness, especially of the air.
• noun Relative humidity.

from The Century Dictionary.

• noun The state of being humid; moisture; dampness; especially, a moderate degree of wetness which is perceptible to the eye or touch.
• noun In meteorology, the amount of aqueous vapor in the atmosphere compared with that which is required to saturate it under the given condition as to temperature: specifically called relative humidity.

from the GNU version of the Collaborative International Dictionary of English.

• noun 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.
• noun The content of water vapor in the air, expressed as a percent of the maximum amount of water vapor that the air can hold at the given temperature; also called relative humidity. The capacity of the air to hold moisture increases with temperature, so if the temperature changes without changing the absolute content of the atmospheric moisture, the relative humidity will also change.
• noun Same as humidity{2}.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun dampness, especially that of the air.
• noun the amount of water vapour in the air.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun wetness in the atmosphere