Barometer

Part of speech: noun

Pronunciation: /bəˈɹɒm.ɪ.tə(ɹ)/

Definitions

1. An instrument that measures atmospheric pressure to predict weather changes and determine altitude
2. A device used to gauge air pressure variations, often employed in meteorology for forecasting and assessing elevation
3. An apparatus for recording changes in the weight of the atmosphere, helping anticipate weather conditions and measure height above sea level

Etymology: Robert Boyle, the Anglo-Irish chemist, gave the instrument its name in 1665, though the device itself had been invented about twenty years earlier by Evangelista Torricelli, a pupil of Galileo. Torricelli's glass tube, inverted over a dish of mercury, showed that the column of liquid rose and fell as the weight of the air above it changed. Boyle needed a name for this new instrument and built it from Greek roots: "barys," meaning heavy, and "metron," meaning measure. The word's meaning therefore began with weight. Air was understood as a substance with heft, and the instrument measured how heavily it pressed down. The "baro-" element is the same one found in "barometric" and in words like "isobar," which joins it to "bar," the unit of pressure, borrowed from the same Greek source. The coinage spread quickly. Soon after Boyle's use, the word was taken into other European languages, and its Greek-based form still serves as the standard term for the instrument across much of the world.

Synonyms: gauge, indicator, measure, meter, test