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.
<-- purified before 1960 -->
© Webster 1913.