aneroid barometer

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A barometer in which variations of atmospheric pressure are indicated by the relative bulges of a thin elastic metal disk covering a partially evacuated chamber.

Wiktionary

1. n. A barometer in which variations in pressure are measured using a partially evacuated capsule whose sides move in and out.

GNU Webster's 1913

1. adj. 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.
2. n. See Aneroid barometer, under Aneroid.

WordNet 3.0

1. n. a barometer that measures pressure without using fluids