Moisture diffused through the air or a solid substance, often causing a slight wetness. The damp in the basement made it feel cold and clammy.
A condition of being slightly wet or humid. The damp in the air made the pages of the book curl.
A depressed or gloomy emotional state; dejection. (dated, usually plural "the damps") He fell into the damps when his proposal was rejected.
A noxious gas, especially methane, that accumulates in coal mines; firedamp. (historical, chiefly British) Early miners feared the damp as much as the darkness underground.