Aneroid, a 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.

An"e*roid (&?;), a. [Gr. 'a priv. + nhro`s wet, moist + -oid: cf. F. anéroïde.] Containing no liquid; -- said of a kind of barometer.

Aneroid barometer, a barometer the action of which depends on the varying pressure of the atmosphere upon the elastic top of a metallic box (shaped like a watch) from which the air has been exhausted. An index shows the variation of pressure.

An"e*roid, n. An aneroid barometer.