MSH: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.,CSP: alkaline metallic element, symbol Na, atomic number 11.,NCI: A mineral needed by the body to keep body fluids in balance. Sodium is found in table salt and in many processed foods. Too much sodium can cause the body to retain water.,NCI: An element with atomic symbol Na, atomic number 11, and atomic weight 23.