English noun: thulium | |||
1. | thulium (substance) 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 | ||
Synonyms | atomic number 69, Tm | ||
Broader (hypernym) | metal, metallic element | ||
Substance meronym | apatite, monazite, xenotime | ||