protactinium
pro·tac·ti·nium
noun
1.
a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
Origin
From proto- + actinium.
Related words
Broader terms
WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). CMU Pronouncing Dictionary. WordNet 2.1 Copyright Princeton University. All rights reserved. Wiktionary content is available under the Creative Commons Attribution-ShareAlike Licence.