plural of lanthanide

(chemistry) Any of the 14 rare earth elements from cerium (or from lanthanum) to lutetium in the periodic table; because their outermost orbitals are empty, they have very similar chemistry; below them are the actinides.

(chemistry, physics) the progressive decrease in the radii of atoms of the lanthanide elements as the atomic number increases; evident in various physical properties of the elements and their compounds

plural of lanthanide contraction