QED QED /ˌkjuː iː ˈdiː/

noun

1. A relativistic quantum theory of the electromagnetic interactions of photons and electrons and muons  ( QED , quantum electrodynamics )
   a relativistic quantum theory of the electromagnetic interactions of photons and electrons and muons
   

phrase

1. () Latin for "which was to be demonstrated." Used to denote the end of a proof of some proposition  ( QED , quod erat demonstrandum )
   Latin for "which was to be demonstrated." Used to denote the end of a proof of some proposition