Also found in: Medical.
hair hygrometer[′her hī′gräm·əd·ər]
A hygrometer in which the sensing element is a bundle of human hair, which is held under slight tension by a spring and which expands and contracts with changes in the moisture of the surrounding air or gas.
An instrument to measure humidity. It uses one or more human hairs, which are held under tension by a spring. The length of hair increases or decreases, depending on the prevalent humidity. Also called a hair hygrometer.