Definitions for: Thulium

[n] 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

Webster (1913) Definition: Thu"li*um, n. [NL. See Thule.] (Chem.)
A rare metallic element of uncertain properties and identity,
said to have been found in the mineral gadolinite.

Synonyms: atomic number 69, Tm

See Also: apatite, metal, metallic element, monazite, xenotime