Science & TechnologyGreek → English
Hydrometer
/haɪˈdrɒmɪtər/noun
A weighted float that shows the density of a liquid by how deep it sinks.
The Greek roots
ὕδωρ
hýdōr
water
μέτρον
métron
measure
Literally: “water measurer”
The story of the word
Around AD 400 Synesius of Cyrene wrote to Hypatia in Alexandria asking her to have a hydroscope made for him, and described a graduated tube weighted at one end, which is this instrument. Brewers, distillers and dairy inspectors turned it into a working tool in the 1700s, since density tells you sugar, alcohol or added water. Nothing about it measures water in particular; the name simply means the thing floats.
- How it travelled
- Ancient Greek → scientific coinage → English
- First recorded
- 1670s
Same family
hydranthydraulicdehydratethermometergeometry
In a sentence
He dropped the hydrometer into the wort and squinted at the reading through the foam.
A cheap hydrometer will tell you whether a car battery is finished.