atomic number 91, n.
a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
<noun.substance>
Pa atomic number 91 protactinium protoactinium
semantic pointers
hypernym
Word
a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
<noun.substance>
Pa atomic number 91 protactinium protoactinium