Aneroid

Aneroid is a barometer, which is generally called aneroid barometer, consisting of a small watch-shaped, air-tight, air-exhausted metallic box, with internal spring-work and an index, affected by the pressure of the air on plates exposed to its action. It is used to measure air pressure by the extent the air deforms the elastic lid of the evacuated chamber.

Aneroid is also something relating to or denoting an aneroid barometer.