barometer

The word 'barometer' is a modern scientific compound formed from two ancient Greek roots. The first part, 'baro-', originates from the Greek noun 'baros', meaning weight or heavy pressure, which itself can be traced back to the Proto-Indo-European root gʷreh₂-, meaning heavy. The second part, '-meter', comes from the Greek 'metron', meaning measure, from the PIE root meh₁-, to measure. Literally meaning "a measurer of weight (or pressure)," the term was coined in the 17th century to name the newly invented device for measuring the pressure exerted by the atmosphere. This literal sense of measuring atmospheric weight evolved naturally into a metaphorical sense, where a 'barometer' became any reliable indicator of changing conditions, such as in economics or public opinion.

Structure: baro (weight) + meter (measure) 'baro' is from Greek 'baros', meaning weight or pressure. 'meter' is from Greek 'metron', meaning a measure or measuring device.