Definition of positronium in English:

positronium

noun

Physics
  • A short-lived neutral system, analogous to an atom, consisting of a positron and a negative electron bound together.

Origin

1940s; earliest use found in Arthur Edward Ruark (b. 1899). From positron + -ium.

Pronunciation

positronium

/ˌpɒzɪˈtrəʊnɪəm/