positronium

Meanings

1. 1
   noun

   an unstable exotic atom consisting of an electron bound to its antiparticle, a positron, with no atomic nucleus

   Positronium usually survives only briefly before the electron and positron annihilate each other.

Formed from positron + -ium. The name follows the pattern of element and bound-state names, although positronium contains no nucleus and consists only of an electron and a positron.

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