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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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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

Vocabulary lists containing molybdenum

Vocabulary from Readings 2, Unit 4

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The miner recorded molybdenum sales of 24 million pounds, higher than first-quarter 2025 sales of 20 million pounds and above the 22 million pounds Freeport had forecast at the start of the year.

From Barron's • Apr. 23, 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

Fourth-quarter production amounted to 640 million pounds of copper, 65,000 ounces of gold and 25 million pounds of molybdenum.

From The Wall Street Journal • Jan. 22, 2026

The nanodots are created from molybdenum oxide, a compound derived from molybdenum.

From Science Daily • Dec. 24, 2025

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

From "Big Science" by Michael Hiltzik

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.