positronium

[ poz-i-troh-nee-uh m ]
/ ˌpɒz ɪˈtroʊ ni əm /

noun Physics.

a short-lived atomic system consisting of a positron and an electron bound together.

Origin of positronium

1945; positron + -ium, coined by A. E. Ruark (born 1899), U.S. physicist

British Dictionary definitions for positronium

positronium
/ (ˌpɒzɪˈtrəʊnɪəm) /

noun

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 for positronium

C20: from positron + -ium