A termination of many English nouns and adjectives from the Latin and Greek.(noun)
In chem., this suffix occurs especiallyin the names of the larger number of the metallic elements.(noun)
The Century Dictionary (Public Domain)
Use "ium" in a sentence
"The IBM device explores the avalanche effect in Germanium, a material currently used in production of microprocessor chips."
"Again, years later a European scientific group changed the name to aluminium -- to line up with the "ium" group of metals, calcium, barium, strontium and so forth, but on this continent that change was never recognized."
"As far as I can tell they pick some scientist from the past or use the location where something was discovered and then attach "ium" to it."