gallium

gal·li·um

noun \ˈgal-ē-əm\

Definition of GALLIUM

: a rare bluish white metallic element that is hard and brittle at low temperatures but melts just above room temperature and expands on freezing and that is used in the form of its hydrated nitrate salt Ga(NO₃)₃·9H₂O to treat hypercalcemia caused by certain cancers—symbol Ga; see element table