a soft silvery metallic element of the rare earth group; isotope 170 emits X-rays and is used in small portable X-ray machines; it occurs in monazite and apatite and xenotime
A metallic chemical element (symbol Tm) with atomic number 69: a fairly soft, easily workable metal with a bright silvery-gray lustre.
The element thulium is named after Thule, a poetic term for Scandinavia. It combines this ancient place name with the chemical suffix -ium.