Cm vs metallic element

Cm and metallic element both are nouns.

Word	Noun	Adjective	Verb	Adverb
Cm	Yes	No	No	No
metallic element	Yes	No	No	No

As nouns, metallic element is a hypernym of Cm; that is, metallic element is a word with a broader meaning than Cm:

Cm: a radioactive transuranic metallic element; produced by bombarding plutonium with helium nuclei
metallic element: any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.

Other hypernyms of Cm include metal.

Cm (noun)	metallic element (noun)
a radioactive transuranic metallic element; produced by bombarding plutonium with helium nuclei	any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.