PROTACTINIUM
protactinium, protoactinium, Pa, atomic number
(noun) a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
Source: WordNet® 3.1
Etymology
Noun
protactinium (uncountable)
A chemical element (symbol Pa) with atomic number 91: a dense, silvery-gray actinide metal.
Synonyms
• protoactinium (dated)
Source: Wiktionary
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Word of the Day
21 April 2025
ENCYCLOPEDIA
(noun) a reference work (often in several volumes) containing articles on various topics (often arranged in alphabetical order) dealing with the entire range of human knowledge or with some particular specialty
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