Caesium
/ˈsiːziəm/noun
A soft, silvery, highly reactive alkali metal of the periodic table.
Did you know?Caesium was named for the bright blue spectral lines seen in its discovery, and that color-based naming comes from the same Latin root that gave English words tied to the color of the heavens.
Etymological Timeline
Latin
Latin
caesius
“bluish-gray or sky-colored”
1860s
Scientific Latin
caesium
“the newly discovered element named for its blue spectral lines”
1861
German
Cäsium
“the element name introduced in scientific chemistry”
Late 19th Century
English
caesium
“the chemical element with atomic number 55”
Modern English
English
caesium
“the alkali metal element cesium/caesium”