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.

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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

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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

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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

The key difference in this new approach is the use of molybdenum diselenide, which has a much higher refractive index.

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

A year earlier, production totaled 1.04 billion pounds of copper, 432,000 ounces of gold and 22 million pounds of molybdenum.

From The Wall Street Journal • Jan. 22, 2026

The capsule itself is made of gelatin coated with cellulose and either molybdenum or tungsten, which prevents any RF signal from being emitted before the pill is swallowed.

From Science Daily • Jan. 13, 2026

When the old vacuum tank was replaced in 1936, Lawrence handed over strips of molybdenum from the interior of the discarded tank to the visiting Emilio Segre.

From "Big Science" by Michael Hiltzik