Psychrometer

Part of speech: noun

Definitions

1. An instrument designed to determine atmospheric humidity by contrasting the temperatures of a wet and dry thermometer
2. A device that assesses moisture content in the air by measuring the temperature difference between two thermometers, one moistened and one dry
3. A measuring instrument that evaluates humidity levels by comparing the readings of a wet and a dry thermometer

Etymology: "Psychrometer" is a technical coinage built from two Greek elements. The first, "psychro-", comes from Greek "psychros", meaning "cold", and the second, "-meter", comes from Greek "metron", meaning "measure". Together they describe an instrument for measuring cold, though the device actually relies on cooling rather than cold itself: the moistened thermometer reads lower because evaporating water draws heat away, and the size of that gap reveals how dry the surrounding air is. The word is a modern scientific formation rather than an ancient one. Ancient Greeks had "psychros" and "metron" separately, but nobody in antiquity built a device with this name, which was assembled from those classical roots to name a hygrometric instrument. The "psychro-" element also appears in other scientific terms, such as "psychrophile", for organisms that thrive in cold conditions.

Synonyms: hygrometer, moisture meter, humidity gauge, thermohygrometer, wet-bulb thermometer