molybdenum

American  

[muh-lib-duh-nuhm] / məˈlɪb də nəm /

noun

Chemistry.

1. a silver-white metallic element, used as an alloy with iron in making hard, high-speed cutting tools. Mo; 95.94; 42; 10.2.

---

molybdenum British  

/ mɒˈlɪbdɪnəm /

noun

1. a very hard ductile silvery-white metallic element occurring principally in molybdenite: used mainly in alloys, esp to harden and strengthen steels. Symbol: Mo; atomic no: 42; atomic wt: 95.94; valency: 2–6; relative density: 10.22; melting pt: 2623°C; boiling pt: 4639°C

---

molybdenum Scientific  

/ mə-lĭb′də-nəm /

1. A hard, silvery-white metallic element that resists corrosion and retains its strength at high temperatures. It is used to harden and toughen steel and to make high-temperature wiring. Molybdenum is an essential trace element in plant metabolism. Atomic number 42; atomic weight 95.96; melting point 2,623°C; boiling point 4,639°C; specific gravity 10.22 (at 20°C); valence 2, 3, 4, 5, 6.

2. See Periodic Table

---

Etymology

Origin of molybdenum

First recorded in 1790–1800; from New Latin molybdēnum, alteration of earlier molybdēna “lead ore,” from Latin molybdaena, from Greek molýbdaina “galena,” equivalent to mólybd(os) “lead” + -aina a suffix indicating relationship or origin

Example Sentences

These results suggest that molybdenum diselenide produced in this way could significantly change how light is controlled in future technologies.

From Science Daily • Apr. 5, 2026

Other companies with recently issued exploitation permits include an anorthosite mining project backed by investors from Denmark and Luxembourg, and a molybdenum project backed by the European Union and run by Canadian company Greenland Resources.

From Barron's • Feb. 14, 2026

For the year, Freeport-McMoRan expects to sell about 3.4 billion pounds of copper, 800,000 ounces of gold and 90 million pounds of molybdenum.

From The Wall Street Journal • Jan. 22, 2026

Once fully operational, it expects the mine to produce around 75,000 tons of copper, around 317,000 ounces of gold and around 1,000 tons of molybdenum over four years.

From The Wall Street Journal • Dec. 3, 2025

At his Palermo laboratory, he worked the Berkeley molybdenum assiduously.

From "Big Science" by Michael Hiltzik