/ bəˈrɒmɪtə(r); NAmE -ˈrɑːm-/ noun
1.
an instrument for measuring air pressure to show when the weather will change :
The barometer is falling (= showing that it will probably rain) .
2.
something that shows the changes that are happening in an economic, social or political situation :
Infant mortality is a reliable barometer of socio-economic conditions.
► baro·metric / ˌbærəˈmetrɪk; NAmE / adjective :
barometric pressure
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WORD ORIGIN
mid 17th cent.: from Greek baros weight + -meter ( see meter ).