Yt‐ter″bi‐um (?), n. [NL., fr. Ytterby, in Sweden. See Erbium.] (Chem.) A rare element of the boron group, sometimes associated with yttrium or other related elements, as in euxenite and gadolinite. Symbol Yb; provisional atomic weight 173.2. Cf. Yttrium.
☞ Ytterbium is associated with other rare elements, and probably has not been prepared in a pure state.