from
The Collaborative International Dictionary of English v.0.48
Humidity \Hu*mid"i*ty\, n. [Cf. F. humidit['e].]
1. 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.
[1913 Webster]
2. Specifically: 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.
[PJC]
{relative humidity} Same as {humidity}[2].
[PJC]
Note: In hygrometrical reports (as of the United States
Signal Service) complete saturation of the air by water
vapor is designated by a relative humidity of 100, and
its partial saturation by smaller numbers in direct
proportion to the actual content of water vapor.
[1913 Webster]