Definition of "protium" []

• The most abundant isotope of hydrogen, H1, with atomic mass 1. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Urey calls heavy hydrogen deuterium and ordinary hydrogen protium."
• "The Staff discussed this and has assigned you to original research for the finding of a better method of the extraction of protium from the ore."
• "The original use of protium had, I found, been discovered late in the Twentieth Century when the protium ores of the"