Metallic element and Polonium

Metallic element noun - Any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc..

Polonium and metallic element are semantically related. In some cases you can replace term "Polonium" with "Metallic element", this terms are similar.

Polonium noun - A radioactive metallic element that is similar to tellurium and bismuth; occurs in uranium ores but can be produced by bombarding bismuth with neutrons in a nuclear reactor.

Metallic element and polonium are semantically related. You can use "Metallic element" instead a noun "Polonium".