The chemical element of atomic number 39, a grayish-white metal generally included among the rare earth elements.
- ‘Edwards notes from chemical analysis that there are traces of yttrium which are undoubtedly of diagenetic origin.’
- ‘Among various radionuclides, yttrium is of particular importance due to its chemical and nuclear characteristics.’
- ‘The elements more abundant in Earth's crust seem to have more mentions - iron and oxygen have far more pages than yttrium and scandium.’
Early 19th century: modern Latin, from Ytterby(see ytterbium).