lutetium -
A metallic chemical element symbol Lu with an atomic number of 71.
Wikipedia
Lutetium is a chemical element with the symbol Lu and atomic number 71. It is in the d-block of the periodic table, not the f-block, but the IUPAC classifies it as a lanthanide. It is one of the elements that traditionally were included in the classification, "rare earths".
OmegaWiki Dictionary
Ω
lutetium Chemical element with symbol Lu and atomic number 71, silvery white lanthanide.