Word Study
lanthanide
CIDE DICTIONARY
lanthanide, n.
Any rare earth element of the lanthanide series (atomic numbers 57 through 71). [WordNet 1.5]
OXFORD DICTIONARY
lanthanide, n. Chem. an element of the lanthanide series.
Idiom
lanthanide series a series of 15 metallic elements from lanthanum to lutetium in the periodic table, having similar chemical properties: also called rare earths (see RARE(1)).
Etymology
G Lanthanid (as LANTHANUM)
For further exploring for "lanthanide" in Webster Dictionary Online