technetium

UK: /tɛkˈniːʃɪəm/ US: (tek nē′shē əm, -shəm)

WordReference Random House Unabridged Dictionary of American English © 2026

tech•ne•ti•um  (tek nē′shē əm, -shəm), n. 

1. Chemistry an element of the manganese family, not found in nature, but obtained in the fission of uranium or by the bombardment of molybdenum. Symbol: Tc;
   at. wt.: 99;
   at. no.: 43;
   sp. gr.: 11.5.

• Greek technēt(ós) artificial (literally, made, verbid of technâsthai; see techno-) + -ium
• 1945–50

Collins Concise English Dictionary © HarperCollins Publishers::

technetium / tɛkˈniːʃɪəm/ noun

1. a silvery-grey metallic element, artificially produced by bombardment of molybdenum by deuterons: used to inhibit corrosion in steel. The radioisotope technetium-99m, with a half-life of six hours, is used in radiotherapy. Symbol: Tc; atomic no: 43; half-life of most stable isotope, ⁹⁷Tc: 2.6 × 10⁶ years; valency: 0, 2, 4, 5, 6, or 7; relative density: 11.50 (calculated); melting pt: 2204°C; boiling pt: 4265°C

Etymology: 20th Century: New Latin, from Greek tekhnētos artificial, from tekhnasthai to devise artificially, from tekhnē skill