Variometer

Part of speech: noun

Definitions

1. A measuring instrument that detects fine changes in altitude or pressure for aviation purposes
2. A device employed to measure subtle shifts in altitude or atmospheric pressure, mainly used in the context of aviation
3. An instrument used in aircraft that indicates the rate at which altitude is changing by detecting pressure variations

Etymology: A variometer is a compound of two Latin-derived parts: "varius," meaning "various" or "changing," and the Greek-derived suffix "-meter," meaning "measure." Together they describe an instrument that measures variation, which in this case means how quickly altitude is changing rather than the altitude itself. The "-meter" ending follows the same pattern as thermometer or barometer, where a Greek-derived suffix attaches to a root describing what is measured. Here the root "varius" points to the shifting quality of the reading, so the device tells a pilot or glider whether they are climbing or descending and at what rate.