Hŷ'gro-scope, n.

n. [Fr. hygroscope, from Gr. ὑγρός, wet, moist, and σκοπός, spying, viewing.] (Physics.) An instrument which shows whether there is more or less moisture in the atmosphere, without indicating its amount, as by the change of weight in substances which readily imbibe moisture, or from the opening and closing of certain seed-vessels of plants, &c.