niton

[nahy-ton] /ˈnaɪ tɒn/
noun
1.
(formerly) radon. Symbol: Nt.
Origin
1910-15; < Latin nit(ēre) to shine + -on1
British Dictionary definitions for niton

niton

/ˈnaɪtɒn/
noun
1.
a less common name for radon
Word Origin
C20: from Latin nitēre to shine