lutetium

American  

[loo-tee-shee-uhm] / luˈti ʃi əm /

Or lutecium

noun

Chemistry.

1. a trivalent rare-earth element. Lu; 174.97; 71.

---

lutetium British  

/ lʊˈtiːʃɪəm /

noun

1. a silvery-white metallic element of the lanthanide series, occurring in monazite and used as a catalyst in cracking, alkylation, and polymerization. Symbol: Lu; atomic no: 71; atomic wt: 174.967; valency: 3; relative density: 9.841; melting pt: 1663°C; boiling pt: 3402°C

---

lutetium Scientific  

/ lo̅o̅-tē′shē-əm /

1. A silvery-white metallic element of the lanthanide series that is used in nuclear technology. Its radioactive isotope is used in determining the age of meteorites. Atomic number 71; atomic weight 174.97; melting point 1,663°C; boiling point 3,395°C; specific gravity 9.840 (at 25°C); valence 3.

2. See Periodic Table

---

Etymology

Origin of lutetium

1905–10; < Latin Lūtēt ( ia ) Paris + -ium

Example Sentences

Heavy rare-earth elements include dysprosium, terbium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium.

From Barron's • Nov. 13, 2025

This unusual imbalance suggested that liquid water had once seeped through the rocks, effectively leaching lutetium out of them.

From Science Daily • Oct. 16, 2025

The 17 elements are: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium.

From Reuters • Jul. 5, 2023

The new material, called nitrogen-doped lutetium hydride, is a blend of hydrogen, the rare-earth metal lutetium and nitrogen.

From Scientific American • Mar. 10, 2023

The team at Rochester started with a small, thin foil of lutetium, a silvery white metal that is among the rarest of rare earth elements, and pressed it between two interlocking diamonds.

From New York Times • Mar. 8, 2023