Ytterbium
Ytterbium , noun
[New Latin, from Ytterby, in Sweden. See Erbium.]
(Chemistry) 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. Compare Yttrium.
Ytterbium is associated with other rare elements, and probably has not been prepared in a pure state.