protoactinium

from the Ancient Greek πρῶτος, prōtos, 'first, ancestor', and the name actinium, as it decays into actinium. In 1918, Lise Meitner and Otto Hahn, on one hand, and Frederick Soddy and John A. Cranston, on the other, almost simultaneously identified this element. Hahn and Meitner named it protoactinium. In 1949, the name was shortened by IUPAC to become protactinium.