PROTIUM
Meaning of PROTIUM in English
/proh"tee euhm, -shee euhm/ , n. Chem.
the lightest and most common isotope of hydrogen. Symbol: H 1
[ 1930-35; PROT- + -IUM ]
Random House Webster's Unabridged English dictionary.
Полный английский словарь Вебстер - Random House .
2012