Densitometers

Part of speech: noun

Definitions

1. Instruments used to measure the density of a substance, such as the mass per unit volume of a liquid, gas or solid
2. Devices that gauge how dense a material is by testing its mass relative to its volume or its optical opacity
3. Measuring tools that determine the compactness of matter, commonly applied in industry, medicine and photographic work

Etymology: "Densitometers" is simply the plural of "densitometer," an instrument for measuring density. The base word "density" comes from Latin "densitas," meaning thickness or compactness, which in turn comes from "densus," meaning thick or dense. The "-o-" is a linking vowel that joins it to "-meter," from Greek "metron," meaning measure. Together the parts describe a device that measures how thick or compact something is. Because the word is built from familiar parts, its meaning is transparent: a "-meter" is any instrument for measuring, as in "thermometer" or "barometer," and the first element names the quantity being measured. The plural simply counts several such instruments, usually in laboratory, printing, or photographic settings where density is checked.