mercury
n. uncountablen. a heavy, silver-colored metal that is liquid at room temperature. It is often used in thermometers and some scientific tools.
n. a heavy, silvery-white metallic element that is liquid at standard temperature and pressure. Often referred to by its chemical symbol Hg.
The mercury in the thermometer rises as the room gets warmer.
Old thermometers contain mercury, which is a toxic substance that requires careful handling if the glass breaks.
Because mercury is the only metal that remains liquid at room temperature, it has historically been used in barometers and electrical switches despite its known neurotoxicity.
Inherited from Middle English Mercurie, from Latin Mercurius.
When referring to the chemical element or the liquid metal, it is uncountable; when capitalized, it refers to the planet closest to the sun.