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positronium

[poz-i-troh-nee-uh m] /ˌpɒz ɪˈtroʊ ni əm/
noun, Physics.
1.
a short-lived atomic system consisting of a positron and an electron bound together.
Origin of positronium
1945
1945; positron + -ium, coined by A. E. Ruark (born 1899), U.S. physicist
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Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for positronium

positronium

/ˌpɒzɪˈtrəʊnɪəm/
noun
1.
(physics) a short-lived entity consisting of a positron and an electron bound together. It decays by annihilation to produce two or three photons
Word Origin
C20: from positron + -ium
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
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