Pycnometer

Part of speech: noun

Pronunciation: /pɪkˈnɒmɪtə(ɹ)/

Definitions

1. An instrument designed for measuring the density of liquids or solids through precise volume displacement
2. A device used to determine the mass of a substance relative to its volume by utilizing fluid displacement techniques
3. A specialized tool that quantifies the density of materials by comparing mass to volume in controlled conditions

Etymology: "Pycnometer" is built from two Ancient Greek words: "puknós," meaning dense or compact, and "métron," meaning measure. The pattern is the same one behind "thermometer" and "barometer," with the first element describing what is measured and the second element "-meter" naming the instrument. A pycnometer, then, is simply a "density measurer." The instrument itself works by displacement. A glass flask of precisely known volume is filled with a sample, and its mass is compared with the mass of the same flask filled with a reference liquid, typically water. Because the volume is fixed, the difference in mass reveals the density of the sample with considerable precision. The word was coined as a technical name for this apparatus, so its Greek parts were assembled deliberately rather than inherited from ordinary speech.