ba ‧ ri ‧ um /ˈbeəriəm $ ˈber-/ BrE AmE noun [uncountable]
[ Date: 1800-1900 ; Language: Greek ; Origin: barytes 'weight' ]
1 . a soft silver-white metal that is used to make ↑ pigment s (=dry coloured powders used to make paints) . It is a chemical ↑ element : symbol Ba.
2 . a barium meal/enema/swallow a substance containing barium that you swallow or that is put in your ↑ bowel s before you have an ↑ X-ray , because it makes the organs in your body easier to see