Yttrium

Yttrium, a rare metal always found in combination with others, and is a blackish-gray powder; the oxide of it, yttria, is a soft whitish powder, and when ignited glows with a pure white light.

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)

Ystradyfodwg * Yucatan
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Young, Robert
Young, Thomas
Young Men's Christian Association
Young People's Society of Christian Endeavour
Youngstown
Ypres
Yriarte, Charles
Yriarte, Thomas de
Ystad
Ystradyfodwg
Yttrium
Yucatan
Yuga
Yukon
Yule
Yule, Sir Henry
Yumboes
Yung-ling
Yunnan
Yuste, St.
Yves