- A lustrous silver-gray metal whose atomic number is 74. It is very hard and dense, ductile, has great corrosion resistance, and has the highest melting point and lowest vapor pressure of all known metals. At elevated temperatures it also has the highest tensile strength. It has almost 35 known isotopes, of which 3 are stable. Its applications include its use as bulb filaments, in electron tubes, in X-ray tubes, hard parts such as rocket nozzles, and in high-speed cutting devices and tools. Its chemical symbol is W. Also called tungsten.