lutetium Definition
lutetiumluteciumnoun 1. chem.(symbol Lu, atomic number 71) a very rare soft silvery metallic element, belonging to the lanthanide series, usually obtained by the processing of other metals, and used as a catalyst and in nuclear technology.
Etymology: 1907: from Latin
Lutetia, the Roman name for an ancient city on the cite of present-day Paris, where it was discovered.