(Science: chemistry, element) A rare element of the boron group, sometimes associated with yttrium or other related elements, as in euxenite and gadolinite. Cf. Yttrium.
Ytterbium is associated with other rare elements, and probably has not been prepared in a pure state.
atomic weight: 173.2
Origin: NL, fr. Ytterby, in Sweden. See Erbium.