A barometer is an instrument that measures air pressure and shows when the weather is changing.
2. countable noun
If something is a barometerof a particular situation, it indicates how things are changing or how things are likely to develop.
In past presidential elections, Missouri has been a barometer of the rest of thecountry. [+ of]
Our sleep pattern is a barometer to our psychological well-being.
barometer in British English
(bəˈrɒmɪtə)
noun
1.
an instrument for measuring atmospheric pressure, usually to determine altitude or weather changes
2.
anything that shows change or impending change
the barometer of social change
Derived forms
barometric (ˌbærəˈmɛtrɪk) or barometrical (ˌbaroˈmetrical)
adjective
barometrically (ˌbaroˈmetrically)
adverb
barometry (baˈrometry)
noun
barometer in American English
(bəˈrɑmətər)
noun
1.
an instrument for measuring atmospheric pressure, esp. an aneroid barometer or an evacuated and graduated glass tube (mercury barometer) in which a column of mercury rises or falls as the pressure of the atmosphere increases or decreases: barometers are used in forecasting changes in the weather or finding height above sea level