kryolith
/ˈkrɪ.ə.lɪθ/Definitions
1. noun
A type of cryogenic material with extremely low thermal conductivity
“The scientist used kryolith to cool the superconducting material to its critical temperature.”
2. noun
A rare or obsolete word for a type of frost or ice
“The 19th-century poet wrote about the eerie beauty of the frost, or kryolith, that had formed on the windows.”