The story
Named after Galileo Galilei, who discovered the principle on it is based: that the density of a liquid changes in proportion to its temperature.
Etymology from Wiktionary, CC BY-SA 4.0.
Galileo thermometer
Today it means: A thermometer made of a sealed glass cylinder containing a clear liquid and several glass vessels of varying densities. As temperature changes, the individual floats rise or fall in proportion to their respective density. Full definition →