Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun protoactinium

1 sense of protoactinium

Sense 1
protactinium, protoactinium, Pa, atomic number 91 -- (a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead)
       => metallic element, metal -- (any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.)