From AMS Glossary
A liquid-in-glass thermometer that uses an organic substance such as alcohol as the thermometric liquid.
This type of thermometer has a very low freezing point and a high coefficient of expansion. The accuracy of thermometers using an organic liquid, however, is much less than that of thermometers using mercury. Spirit thermometers are used when the low freezing point is important, and in such special application as the minimum thermometer.
Middleton, W. E. K., and A. F. Spilhaus 1953. Meteorological Instruments. 3d ed., rev., . 73–75.