- a silver-white metallic element, used as an alloy with iron in making hard, high-speed cutting tools. Symbol: Mo; atomic weight: 95.94; atomic number: 42; specific gravity: 10.2.
- 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
n.metallic element, 1816, from molybdena, used generally for lead-like minerals, from Greek molybdos “lead,” also “black graphite,” related to Latin plumbum “lead” (see plumb (n.)), and like it probably borrowed from a lost Mediterranean language, perhaps Iberian. The element so called because of its resemblance to lead ore. n. Symbol Mo
- A hard metallic element that is an essential trace element in plant and animal nutrition. Atomic number 42.
- 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. See Periodic Table.