 protoactinium |
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| 1. | [ noun ] (chemistry) a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead | |
| Synonyms: | Pa atomic_number_91 protactinium | |
| Related terms: | metallic_element | |
| Similar spelling: |
protactinium protectionism protectionist protoctist protection protecting Protoctista protesting |
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