lanthanide

The lanthanide (or lanthanoid) series comprises the 15 elements with atomic numbers 57 through 71, from lanthanum to lutetium. All lanthanides are f-block elements, corresponding to the filling of the 4f electron shell, except for lutetium which is a d-block lanthanide. The lanthanide series is named after lanthanum.
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Noun
1. any element of the lanthanide series (atomic numbers 57 through 71)
(synonym) rare earth, rare-earth element, lanthanoid, lanthanon
(hypernym) group, grouping
(hyponym) terbium metal

n. lanthanide

La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb

Compare with actinide and inner transition metals.Elements 57-70 are called lanthanides. Electrons added during the Aufbau construction of lanthanide atoms go into the 4f subshell.