- A silvery-white metal chemical element whose atomic number is 56. It is an alkaline-earth metal, extremely reactive, and has around 30 known isotopes, of which several are stable. Barium is extrudable, machinable, and slightly malleable. It is used, for instance, as an atomic tracer for radium, in spark-plug alloys, and as a getter in vacuum tubes. Its chemical symbol is Ba.
- chemical symbolBa
- noun a metal used in x-rays of the stomach and digestive tract.
- noun a chemical element, forming poisonous compounds, used as a contrast medium when taking X-ray photographs of soft tissue