- yttrium, Y, atomic number 39 - a silvery metallic element that is common in rare-earth minerals; used in magnesium and aluminum alloys
--1 is a kind of metallic element, metal
--1 is a substance of gadolinite, ytterbite; fergusonite; xenotime - Y - the 25th letter of the Roman alphabet
--2 is a kind of letter, letter of the alphabet, alphabetic character
--2 is a member of Roman alphabet, Latin alphabet