nouna soft malleable silvery-grey element of the lanthanide series of metals, occurring in gadolinite and monazite and used in lasers and for doping solid-state devices. Symbol: Tb; atomic no: 65; atomic wt: 158.92534; valency: 3 or 4; relative density: 8.230; melting pt: 1356°C; boiling pt: 3230°C
Word origin
C19: from New Latin, named after
Ytterby, Sweden, village where it was discovered