lanthanoid

Example:The lanthanide series includes elements that are essential for making strong magnets in modern electronics.

Definition:The group of fifteen metallic elements that are chemically similar to lanthanum but are not chemically identical to it; they include erbium and yttrium in addition to the fifteen lanthanide elements.

Example:China is the largest producer of rare-earth elements, including the lanthanoid elements.

Definition:A group of metallic elements of the lanthanide series, along with the elements scandium and yttrium, valued for their rare occurrence in the Earth's crust and for the unusual optical and electronic properties of their compounds.